This is literally the opposite of reality. The private/VC market is not relevant here. We’re strictly talking about publicly traded companies.

No this is actually true. Most stocks do go down (or at least only match much less risky investments like short-term bonds), but the stock market goes up because some stocks go up a lot. This is why all investors diversify. For example, the Russel 3000 Index goes up ~10% a year because they remove bad stocks and replace them with ones that seem better. But, employment at a single company with stock-based compensation is a concentrated bet on that single stock during the employment timeframe.

Recently learned this from the excellent and very pithy Michael Batnick blog https://theirrelevantinvestor.com/2020/09/10/most-stocks-suc... who was citing https://wpcarey.asu.edu/department-finance/faculty-research/...

I agree the stock market has positive skew but in your career you will have enough bets to smooth out the effects of betting on a single stock. Additionally, you're not really making the same bet as an equity investor because your bet has optionality. Your downside is capped at less than a year in loss earnings because if the stock goes down and the company cannot bring you back up to market rate you just switch companies. If the stock goes up, you enjoy 4 years of above market compensation before getting reset to market rate.

I've never been in the situation of a significantly down price over more than a year. Is it normal that the firm will give 'refreshers' to get back to the target comp in that case?