This is putting the cart before the horse. There is no such thing as what the players should earn, and the level of expenses borne by them are ultimately unimportant. The players can only earn to the extent that they produce revenue for event producers, who are spread pretty thin.
Expenses are estimable before one enters a tournament, as are prize money payout structures. The choice by a player to participate in a pool tournament constitutes an investment of time and money. Anyone who feels that it is a poor investment need not participate.
Of course, we'd all like to see the players make more money, but it's not on the event producers that they don't. If the event producers do not turn a profit, they will walk from the game. Making ends meet is no easy task for an event producer. Unless the game continues to grow, all but the top 25 or so players will be hard pressed to earn a substantial living.
That said, how many events are there on the world pool calendar having a first prize of $25,000 or more. I'd bet it's close to 30 and probably more. Pool offers a lot of high paydays now and the worthy can make quite a big income.