Not if you work in a private company. And even if you do sell stock immediately, if the stock price goes down so does your actual compensation. Equity compensation is less certain than salary compensation.
I suppose, but how many late-stage private companies (i.e. late enough that you're getting stocks instead of some kind of option or other you-aren't-technically-gaining-anything vehicle) are having wild downswings in stock price? I'm not aware of any, and while I could imagine there are some I would assume it's a relatively small number, but I could just not be in the loop.
Dropbox and Twitter both experienced drops in stock value of ~40%. Uber and Lyft both lost a third of their stock value since July. Washington is consistently taking about tougher regulations for tech companies. I would not assume that tech stocks are going to be stable in the near future.