I mean on that standpoint if an employee at Meta fucks something up on the scale of $80B they won't get fired if the stock and revenues are doing well?
An employee of Meta is that, an employee of Meta. Their responsibilities extend to the requirements of their direct boss and are not subject purely stock and revenues. A CEO is an employee of the board and shareholders. Their responsibilities extend to creating returns and thus their performance is wholly defined by stock and revenues.
You're right though he can't be fired in general, but the point is: why would anyone fire him? He is demonstrating great performance.
To revert back to your example with a personal example, I have once before directly caused an outage at a facility that cost us 1/6th of our yearly turnover. I wasn't fired, why? It was a question of value. Would someone else not make the fuckup? What is the cost of replacing me with someone who may make a similar fuckup? And more importantly how much value do I provide beyond that fuck-up. Fun fact I got an "exceeded expectation" on my year end review and a nice bonus.
How's this relate to CEOs? Shareholders expect CEOs to not just sit around and let the ship run. They expect especially in the technology world for CEOs to try something new - especially when it means entering new markets with potential new revenue streams, and there's not only an acceptance that some of this costs money without payoffs, there's an outright expectation for it.
Large numbers play against us here. In terms of units of revenue Meta's *expenditure* in something like AI is not out of the ordinary for R&D investment any tech company makes. In fact it's on the low side. People just can't comprehend this because they loose touch with just how much filthy fucking money floats around Meta. When you knock a zero off the back of it, and give it any other company name you don't blink an eye.