So, the lottery is better than a savings account, because if you win the upside is much higher? Whether or not stocks options/rsus/whatever are worth more than an increase in salary is very dependent on the timing, the company, and variety of other things. You can just as easily point out losing situations as you can winning; in fact, I'd wager the losing is more common.
It's a fairly controlled bet with relatively little downside (companies are likely to cover a large drop in RSU value) and a lot of upside. Since the vesting window is 4 years, you can sell as soon as things best, you still get a salary and you can switch jobs at any time the risk isn't that high. And since you can make up a decade of regular income in a few years the logical approach is to roll dice when younger if you can.
