People buy for a number of reasons. Among them being age(having as old as possible), and skills(having as low as possible). One explanation for an old, essentially worthless player would be a low salary to use as scrimmage fodder that eventually pays for itself.
I have 1757 players for sale and I'm $25,835,360 in debt. Buy them at outrageous prices, or be selfish and make me go bankrupt. You decide, BB.