As a boy, Brian L. Roberts watched his father, Ralph, build Comcast into a cable empire.  Brian was eager to help his dad, shadowing him at the company’s Philadelphia offices on Saturdays, paying his dues as a door-to-door salesman and tower repairman, and positioning himself as the clear successor among five siblings.  When the younger Mr. Roberts became Comcast’s chief executive in 2002, he continued his father’s daring deal making, transforming the company into a giant media conglomerate. Last year, he struck a $45 billion deal for Time Warner Cable that would join the country’s two largest cable providers and create a television and Internet behemoth.  But on Friday, Mr. Roberts’s ambitions crashed headlong into a stepped-up regulatory regime in Washington. Comcast suffered an ignominious and humbling defeat, withdrawing its proposed acquisition more than a year after announcing it.  While Mr. Roberts, 55, has had great success expanding Comcast’s business and extending its influence — his audacious acquisition of NBCUniversal reordered the TV landscape — he has also, at times, overplayed his hand.  “We gotta move on,” says Brian L. Roberts, Comcast’s chief executive, on abandoning the cable giant’s $45 billion bid for Time Warner Cable.  “There is some element of hubris by continuing to reach for these things,” said James McQuivey, an analyst at Forrester Research.  The collapse of the Time Warner Cable deal was not the company’s first misstep. In 2004, Comcast made a surprise $66 billion offer for the Walt Disney Company, which it later withdrew. Shortly before taking over as chief executive, Mr. Roberts assisted his father in trying to acquire MediaOne Group, but lost out to AT&T. Now Comcast must chart a path forward after another botched megadeal.  But Mr. McQuivey added that for a company like Comcast, taking big and risky bets is part of its business plan. “You only get to be the biggest cable company and largest broadband provider in the country by swinging for the fences,” Mr. McQuivey said.  Many believe that no matter how big Comcast gets — it is already the country’s largest pay-TV operator and the only big company that runs cable systems and owns big content studios — the Roberts family will not be satisfied.  Mr. Roberts declined an interview request on Friday. But his executive team praised his appetite for risk taking and made no apologies for its failed attempt to buy Time Warner Cable.  “He’s ambitious for the company,” said Stephen Burke, chief executive of NBCUniversal. “The way you do that is by doing big deals. You can’t grow that quickly organically. Companies that break out do big, defining transactions, and we do more than most. That’s a credit to Brian.”  Those close to the family say that Mr. Roberts still enjoys the support of his father, now 95, who has encouraged him to dream big. “Ralph has given Brian the confidence to go and do these big deals,” Mr. Burke said.  In fact, supporters argue that Mr. Roberts is more cautious than his father was while building Comcast several decades ago.  “I actually think that Brian is more conservative than Ralph,” said Michael Angelakis, Comcast’s chief financial officer, noting that Comcast had a pristine credit rating and robust balance sheet.  “In the days of Ralph building his company, they were borrowing junk-bond-type debt, they were leveraging the balance sheet pretty dramatically,” Mr. Angelakis said.  Even Comcast’s contribution to the Philadelphia skyline — the city’s tallest skyscraper, and another, taller building under construction and designed by Norman Foster — are not as audacious as they might seem.  “Brian Roberts is a very cautious guy, despite his big ambitions,” said Inga Saffron, the architecture critic for the Philadelphia Inquirer, who knows the Roberts family socially. “Neither one of these towers is super showy.” Ms. Saffron also noted that Comcast owns neither building, limiting the company’s financial risk.  The muted architecture of Comcast’s towers is in keeping with Mr. Roberts’s low-key countenance. At the same time, there is nothing understated about his profile at the helm of one of the country’s most powerful media companies.  A major Democratic supporter, Mr. Roberts has golfed with President Obama on Martha’s Vineyard. He negotiated the deal for Time Warner Cable from the Winter Olympics in Sochi, juggling calls with bankers and lawyers in between state dinners with President Vladimir V. Putin of Russia and meetings with his NBC team covering the Games.  Comcast took precautions in the event the deal fell apart, declining to offer Time Warner Cable a breakup fee and ultimately saving itself billions of dollars.  “We take very calculated and educated risks on all the investments we make,” Mr. Angelakis said. “One of the things we are very good at is assessing risk.”  And while its most recent deal is in tatters, other media executives said that the father and son behind Comcast possessed the foresight and conviction necessary in a constantly changing industry dominated by big personalities.  “The differentiator about the Roberts, from almost everyone else they compete with, is that they are always about seizing the next opportunity,” the media mogul Barry Diller said in an email. “You have to be bold enough to reach beyond your current grasp. That sometimes it doesn’t work out isn’t particularly meaningful.”  The elder Mr. Roberts, genteel and bow-tied, was an entrepreneur, selling golf clubs, working for Muzak and owning a suspenders company, before taking over a small cable operator in Tupelo, Miss., in 1963 and growing it from there. He built Comcast by rolling up smaller cable companies and investing in television networks like QVC, the Golf Channel and E! Entertainment Networks.  By the time Brian took on a major role at the company, Comcast had established itself as a major media-industry power, and the opportunities — and potential missteps — were that much more enormous.  In 1997, not yet chief executive, Mr. Roberts negotiated with Bill Gates to sell 10 percent of Comcast to Microsoft for $1 billion. Four years later, he suggested Comcast acquire AT&T Broadband for $52 billion, a deal that gave him control of the biggest cable company in the country.  After Comcast acquired NBCUniversal, Mr. Roberts said the company was unlikely to strike another megadeal any time soon. Then came Time Warner Cable.  On Friday, Comcast executives once again pledged that it was committed to its core business and in no rush to chase another acquisition.  “We’re strategically complete,” Mr. Burke said. “We’re the biggest cable company, we have a movie studio, a broadcast network, the top cable network, and theme parks.”  Several analysts, however, said it would only be a matter of time before Comcast was on the hunt for another big deal.  “While occasionally it doesn’t work in specific cases,” Mr. McQuivey said, “whatever they’re doing seems to be working out well enough to justify continuing.”  A version of this article appears in print on April 25, 2015, on page B1 of the New York edition with the headline: Comcast Withdraws Purchase Bid, but It Isn’t Going Anywhere. Order Reprints| Today's Paper|Subscribe
Comcast suffered a setback as it canceled its offer for Time Warner Cable, but the executive at the company’s helm will likely continue in his father’s footsteps as a daring deal maker.