question:  What motivated the leprechauns to build a spaceship?
context: Every writer must seek his own Flowery Kingdom in imagination's wide demesne, and if that search can begin and end on Earth his problem has been greatly simplified. A one-time Air Force officer, he has turned to fantasy in his lighter moments, to bring us such brightly sparkling little gems as this. Walt Sheldon The tiny spaceship had been built for a journey to a star. But its small, mischievous pilots had a rendezvous with destiny—on Earth. You may call it gas, if you wish, for we treated it like gas at the center for convenience—as it came from the rocket tubes in our engine. Without this coefficient to give us control, we would have lacked a workable equation when we set about putting the first moon rocket around those extraordinary engines of ours, which were still in the undeveloped blueprint stage. I had to figure everything into it—diameter of the nozzle, sharpness of the edge, the velocity of approach to the point of discharge, atomic weight and structure— Oh, there is so much of this that if you're not a nuclear engineer yourself it's certain to weary you. Perhaps you had better take my word for it that without this equation—correctly stated, mind you—mankind would be well advised not to make a first trip to the moon. I had seen them first as a boy of eight, and then, very briefly again, on my tenth birthday. I smiled, and the foreman of the leprechauns—if that's what he was—saw me smile and became stiff and alert for a moment, as though suspecting that perhaps I actually could see him. Or so the legends affirmed, though I've wondered often about the truth of them. Of course it was a spaceship, or a miniature replica of one. I shook my head in wonder, then stepped back from the spaceship and looked about the glade. So I stepped back to the tiny spaceship, and this time I struck it a resounding blow with my fist.
output:  They believe that humans' obsession with technology will make the world inhabitable
options:  They desire to seek and add more riches to their already expansive collection  They believe that humans' obsession with technology will make the world inhabitable  They fear that their race will soon become extinct due to population decline  They wish to transport their riches to another location where humans will never steal it