I'm pretty sure a first year security engineer at Facebook gets paid a lot more than $5k too. They're not your employer, they don't owe you money, if you want to mess around looking for security vulnerabilities in your free time it's good of them to pay you at all.
I fully support Facebook paying bug bounties, but let's compare apples to apples here.
FB's first years only get $50k? In Bay Area California??? WTF world am I living in where people actually get compensated properly? The past few days I've seen posts where compensation at very respectable companies is abysmal!
Edit: Apologies for not reading it correctly. I now stand corrected that the parent meant a $50k signing bonus in addition to a more reasonable annual compensation.
The parent poster was sarcastically pointing out that entry level engineers who are likely not contributing much to Facebook's bottom line are compensated way more than the security researchers finding these potentially costly vulnerabilities.