Another relevant factor I think, is the kind of challenges you must overcome in politics vs technology.
A scientist probably finds the challenges to overcome in technology much more intellectually stimulating than she finds the challenges in politics. Which makes sense because people tend to get good at things they enjoy, and scientists need to get good at overcoming challenges much like technological challenges.
Bingo. Thanks for writing this more clearly and succinctly than I could!
Even though making laws or doing science both require writing and documentation, the challenge in a lab or on a computer is very different than coalition building amongst hundreds of very different people.
A scientist probably finds the challenges to overcome in technology much more intellectually stimulating than she finds the challenges in politics. Which makes sense because people tend to get good at things they enjoy, and scientists need to get good at overcoming challenges much like technological challenges.