If you seriously think the frontier labs are dangerously playing with everyone’s lives (how many companies can even claim this civilisational scale) then why would you be ok with holding vested shares which will grow in value if the corporation achieves what it aims to achieve?

At the very least you can sell them (they’re not so illiquid considering the company’s hype and success) and invest in the broad market.

Debatable, and clearly not clear. It's weird to say this when there are obvious counter examples staring us in the face, not least of all the founder of the company he just left, of who (Dario) people could have said the same thing when he left OpenAI.

Granted, there is less likelihood now then there was then but this much is clear: if he starts his own company, he may make more.