I've had shares worth millions on paper that later turned out to be worthless many times... It really need to be a later stage startup with real traction for that to really mean anything.
However, it's a different path for top executives versus the rest of us.
If you follow folks at that level, you'll notice that even when their startup fizzles, they tend to come out on top.
There are ways to get paid well at an exit even when your stock are nominally worthless. If you're an executive. Not to mention that if their startup was worth $100m+ at one point, they would likely get a chance to start another.
None of this is criticism, by the way: many of these guys worked harder and longer than most engineers.
They did get disproportionately compensated for it, though.
Congrats, you just got paid $30m+ as an exec for an exit that paid nothing to all other shareholders.