Football has global appeal as entertainment, so the market for football is enormous. The volume of TV audiences mean advertisers want to get on board, it's worth a lot of TV broadcasters who sell subscriptions because people will buy it and it's a hobby of very rich people who want to pump money in to the game.
So the question is, given that the market is so big and the product is worth so much, who should get it.
It's either the players or it's the club owners, or its the peripheral people like agents and so on who cream money out of it.
Unlike a lot of fields, the workers (players) actually have a lot of market power here and aren't subject to having their wages driven down by owners who are enjoying most of the profits. Actually owning a football club isn't very profitable, the super rich buy football clubs as a hobby to spend their money not a way to make money. So given the amount of money in the game, there are a lot of profits to be made and the profits will go somewhere - so if not to the players who should get them...?
Now the other argument is about the level of inequality in society and whether footballers, bankers, property magnates etc should have so much and whether it's right that over time a greater and greater proportion of wealth in society is being concentrated at the top. That's not just a football argument though, and that's about the extent to which government should intervene by increasing taxes at the top to use the extra revenue for social investment, public services etc.