SETI@home is a pure scientific experiment. We are searching on the basis of a sound hypothesis. That is reason enough to participate. I believe in using my spare cpu cycles for such a scientific experiment. Will we ever find live outside our planet..possible. Will it be with this experiment. I do not think so. But that doesn't mean that we shouldn't look. I could be wrong ;)
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.