When you accepted the job, you knew the terms. Those included not getting equity, and those included carrying some risk with known reward.

I don't see how the owners selling retroactively makes the risk-reward balance different. Unless you consider it a risk/downside that someone else gets a windfall and you don't get to share. That seems silly to me tho. How rich someone else is does not affect how much money I need to live, with a few exceptions (inflation, friends, power dynamics in pre-existing relationships).