And how much your boss likes you.
And on a related subject, why do actors and pro athletes make so much money?
They didn't always, even in recent history. Same with artists. Even today, only a few make the bigtime.
They couln't make that much money if nobody was willing to pay it, so there must be a big enough pool of money, somehow, to feed the pigs. Public popularity is what drives much of it, and in the case of sports, public money too. The taxpayers put up the venue, freeing up big bucks for the players.