Supply + demand + dash of monopoly.
Players like Trout are in short supply. Therefore he is in high demand.
Add in the fact that the major sports leagues have a near-monopoly on consumers (with a tight grip on stadium and broadcast revenue), with a license to print money, and you end up with Trout.
Eventually the whole system will become too heavy to sustain itself, and you'll see teams that are so far underwater that they'll have to declare bankruptcy.
Anyway, I'm not too bothered by this. Let the Angels fans pay for him if that's what they want to do.