It's altogether different point what market gives to that person. Market generally rewards anyone irrespective of their actual merits, because market works on apparent merits and anyone good at selling themselves succeed.
Ponzi was a very good example of how markets work. [1]
Yahoo as well might have allowed itself to get "ponzied". That's their foolishness and they are paying its price.
[1] https://en.wikipedia.org/wiki/Ponzi_scheme
Edit: typo and added link
Case in point is that worth of Mayers might depend on far too many factors which we cant comprehend and we must not judge her.
It's also a very risky and short lived career.
The downside protection afforded to CEOs is ridiculous - heads I win, tails you lose.
The problem is that companies are over reliant on a single leadership figure. This makes little sense in large companies with lots of complex divisions and interests. Does it really make sense to rely on a single person to guide the company?
But it is market that often determines these numbers and we simply do not possess the information to look at all those variables.