Reason Number 10

Colonization: it's a long shot, but there are serious people who still claim that we can travel to mars and turn it into livable space for humankind. The process is called "terraforming".

Reason Number 9

Intelligence Surveillance: Ok maybe we wouldn't bother placing a spy satellite over the Hawaiian Tropics contest (then again maybe we would) but the very first truly functional (i.e. non-experimental) satellite was a U.S. spy satellite. This was the Corona series, first operational in August of 1960. The U.S. maintained a strong lead in this super-secret technology throughout the cold war and it was the only distinct intelligence advantage this nation ever really had. Since the U.S. won the cold war, you simply can't dismiss the importance of this capability.

Reason Number 8

International Diplomacy: this one speaks for itself. It's the only reason we went to the moon.

Reason Number 7

Natural Resources: this one may be reaching, but there are people who believe that we would want to mine the asteroids & the moon for minerals. The most credible argument for this is assuming we would want to build a huge space structure and wouldn't want to have to loft the raw material into earth orbit or higher on rocket power.

Reason Number 6

Researching the universe: this one also speaks for itself. The discoveries and observations made from the Hubble telescope alone are staggering, and could never have been made from earth because of the obscuring effect of the atmosphere.

There are new discoveries being made every day, such as finding planets around other stars and discovering the true structure of the outer solar system (the Kuiper belt).

Reason Number 5

Technology Spin-Offs: this also speaks for itself, although the list of new technologies just goes on and on and on. These new technologies mean new industries, new jobs, and saved lives. For example, kidney dialysis, which has kept (and still keeps) countless people alive, came from the Apollo program. A new artificial heart came from technology used in Space Shuttle. New insulin pumps can eliminate the need for injections for diabetics, and the space program is constantly producing new materials for prosthetic devices.