Same reason you still play Blo- er, post on the BLF: because it's fun. Also what they said about it being a celebration of nations and such. Also, the "we could spend it on the space program instead" argument assumes that there are literally only two things being funded in the entire world. Plus, NASA is funded by the U.S. Government, while the Olympics are funded by the organization that organizes the Olympics plus the host nation. Further, if you wanted to cut something to fund NASA, cut the military budget. I'm sure we don't need ten different supercarriers, given that we are not going to be fighting a naval war with any other nation anytime soon.