The US space program has been extremely beneficial in other areas in addition to space exploration. A great deal of the science we rely on today, and not just in computer technology, can be directly attributed to the space program (Velcro comes to mind
). There have also been advancements in medical science through experiments conducted in zero gravity. The money spent creates jobs in a number of fields and stimulates the economy (one of JFK's reasons for starting "the space race"). It is basically an R&D program and, as is most often the case with any company, the costs are high but the benefits tend to outweigh the costs.
The space program isn't about making contact with little green aliens. It's about exploring and learning about the universe to which we belong. Knowledge is power, not power to subjugate, but to give us information that may be necessary to overcome problems on our own planet.