I don't see anything rude about it, but YMMV.
it is already implemented for different reasons in professional sports
Yes, I'm quite aware. The thing is, athletes who choose to, say, play in the NFL voluntarily accept the terms of the agreement between the NFL and the NFLPA. If they don't like it, they can get a job doing something else.
I was just extending this concept for all professionals
And that's the problem. Who's going to tell someone what their universal "salary cap" is - and what possible standing could they have to make such an assertion? Who has any standing to tell me I can't negotiate whatever terms I can reach with a prospective employer? Or maybe I do purely service based work where the more hours I work, the more $$$ I make. Who can tell me that there's a limit (other than that imposed by physical reality) to how many hours I can work?
will somehow discourage people from running this rat race and accumulating so much wealth.
Maybe some people like the rat race? Or at least find the prospective reward sufficiently motivating so as to justify participation. As long as its voluntary, it's really no one else's business.
It will inevitably put in every person mind the idea of work and personal life balance.
Great. But for me, that's my decision to make, not yours, or anyone else's. This is my life and I'm the one in control. Likewise I have no standing to dictate the terms of how you live your life.