 Why does Johnson stay on the asteroid, even though few people come by?
The interplanetary con-men drank noisily, asked for more, until they had drunk eight glasses. Then Johnson rubbed his thumb on his index finger and wetted his lips expectantly. After giving them directions that would take them to the free-water pool, the ponderous factotum of Planetoid 42 shook hands and headed back to the saloon. It was on the sixth trip that Joe caught a glimpse of Jupiter-shine on a bright surface off to the left. Johnson's eight-foot son, topped by a massive roof of sun-bleached hair and held up by a foundation that seemed immovable, had obviously been born and raised in low gravity. Instead of replying, Harvey hurried outside to the ungainly second-hand rocket ship in the center of the shabby spaceport.
 Here he's able to take advantage of travelers who are lost or in need of supplies.
 Here he's able to meet traders like Harvey and Joe and barter with them.  He's able to run business even with few customers.  Here he's able to take advantage of travelers who are lost or in need of supplies.  He doesn't want to give up the spring of water.