It's true that people doing PhD's aren't monetarily driven but you can easily imagine that incentives change once they start a family and have to worry about things like a mortgage, college tuition for their kids, etc. If you can get a significant pay raise while maintaining some semblance of research autonomy AND have greater impact, why not go for it?

As I mentioned, a CS professor with enough seniority to have a family to raise is going to be pulling a 200k+/year salary, more than enough to comfortably raise a family, even in the Bay Area (probably not SF).

Something I didn't mention earlier is also the fact that if they really needed extra money they can easily consult on the side, as well, which is totally okay in academia (unlike most employees at companies).

> they can easily consult on the side, as well, which is totally okay in academia (unlike most employees at companies).

It is very rare to be outright prohibited from consulting on the side as an employee. I currently do exactly that (work for a company that sells consultants and developers to its clients on contract) and we are only prohibited from doing the same on the side if it is a conflict of interest. I've never heard of someone going to their supervisor with a lead and being told they could not pursue it.

Yes, it is rare to be outright prohibited. But it will definitely be looked down upon by managers. It is also culturally uncommon. Very few Google engineers are consulting on the side, for example.

It is extremely common for CS professors to consult. And there are absolutely no conflict of interest restrictions. CS professors will consult in their direct area of research.

  a CS professor with enough seniority to have a family
  [...] is going to be pulling [...] more than enough to
  comfortably raise a family

So you're saying people who are paid enough to have a family are going to be paid enough to have a family? :)

You think you're being clever, but you're not. Seniority actually matters in academia.

What I'm saying is I know people who've started families while they were postdocs or even phd students. Academics can start families at any level of seniority.

And if the country's policy is "well of course you're struggling to support your family, it's your own fault for not waiting until you achieve tenure at average age 39" [1] well I can understand academics leaving academia for industry. The average age of first childbirth in the US is 26, with steep rises in complications beyond age 35 [2].

Unless you're a man planning to have a child with a woman 10 years your junior, getting tenure before having a child doesn't sound like a great idea to me.

[1] https://en.wikipedia.org/wiki/Professors_in_the_United_State... [2] https://en.wikipedia.org/wiki/Advanced_maternal_age