Robert Samuelson (Newsweek) has an article about the much touted knowledge gap. But it is what Samuelson said about why people choose a career in science that rang most true:
Only about 4 percent of the U.S. workforce consists of scientists and engineers. Having an adequate supply depends on what thousands—not millions—of smart college students decide every year to do with their lives. People choose a career partly because it suits their interests. This applies especially to science. "Physics is like sex," the physicist Richard Feynman famously quipped. "Sure, it may give some practical results, but that's not why we do it."