> Isn't the incentive getting paid?

No, humans are not coin-operated robots. There is an entire field of psychology dedicated to this:

https://en.wikipedia.org/wiki/Industrial_and_organizational_...

Also it's very well known that most people are willing to accept salaries below market rates to work on topics/goal/environments they really care about.

Equally, many work in ethically controversial organizations because of higher salaries.