I run SETI because whilst my computer is sitting there doing nothing but use electric and occasionally downloading things it might as well be doing something constructive! Also it helps the scientific community and i like to support them as they say if you can't beat em join em!
I believe that the Univere is way too big to just have one intelligent life form living in it, maybe only one lives in any specific time period and when we die out in 10 million years (or when ever it may be) another species will rise like our ancestors in a different galaxy on a world similar to ours. Who knows but i think there is definitely something to find.
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.