When I left Epic, they had just reneged on an equity compensation promise by issuing me some form of "shadow" stock tokens, because they didn't want to bring their number of real owners up past a point that would trigger automatic financial disclosures. I read the accompanying paperwork, and decided that I needed to kick my job search into an even higher gear, immediately. Just one of the many reasons I had for moving on. (2007)
At that time, they were not offering salaries that were even competitive with other companies in Madison. Never mind about Seattle or SV. I had four managers in 2.25 years, because three of them left for higher pay elsewhere almost as soon as they got promoted. I left the fourth for ~20% higher pay.
I would guess that any major tech employer could stroll into town and hire the best 50% from under Epic's feet in less than two weeks, while still saving money on salaries compared to SV. Queen Judy is not taking that company public, and would rather divert her profits to charity than to employees. There won't be options or RSUs. The only reason people might stick around is the cult-like atmosphere.