VC investors look aim for 12% return, approx 3x over 10 years. But returns are hugely variable (power law?), so returns heavily dependent on one winner e.g. one success at 30x out of 10 investments gives 3x.

Your numbers don't work unless you can get 10x returns on 3 out of 10 investments (which seems unlikely).

https://techcrunch.com/2017/06/01/the-meeting-that-showed-me...

Edit: And how far is that $250k going to stretch on salaries, especially over a few years!