My understanding is that the underwriting bank and early investors and institutional investors win first, then founders, after that early employees. Usually offloaded onto the robinhood crowd who excitedly buys in.
Employee shares usually get put in a 3-6 month lockdown so they don't get to participate in the bubbly robinhood excitement.
According to this analysis of Anthropic's S-1, the founders own about 10% of the company, which at $2T valuation would mean they each make about $28B. The employees collectively own about 15% which results in some staggering math - thousands of employees making ~$100M each, even those hired as recently as last year.
These are averages, but still!
https://x.com/AndrewBenson/status/2115458726396310008