At my last company, the stock price when I joined was at $150/share, it rose to over $200/share and crashed to under $30/share by the time my initial vesting date came. I lost six figures of expected TC based on my original offer (over half my total compensation). Since it was a 1 year cliff, I couldn't do anything to diversify or limit my risk because my RSUs were not mine until they vested.

Lesson learned, but I don't think there's an archetype of engineer that prefers that kind of risk profile over large cash payments each month. My downside for Y1 at Amazon is 4% of the agreed upon TC.