Maybe you mix academic career with a business one. I talk about an academic career, that means that the folks never put there nose out of the university. ::) Hardly...
In many areas of academia, people "venture out" from the university ...
- Professors in the hard sciences do consulting work for engineering firms
- Professors at medical universities are still involved in practicing medicine
- Computer science teachers, like math and physics teachers, are often involved in different contract/consulting engagements
- My wife, who was a French teacher, told me about many instances where foreign language teachers make some pretty decent money as translators