Quote from Rick_Dthe only problem with space exploration is that it isn't 1950 anymore and we know there's nothing out there except certain death for anyone stupid enough to try.
The Apollo program created $14 for every $1 it cost (according to Brian Cox), through jobs, technology etc.
One asteroid could contain the entire world's wealth in raw materials.
NASA is also a science organisation so learning about the history/geology of planets, possibility of life etc by exploring those is a valid use of its funds, even if people don't see any direct benefits to their lives.