This day-trading it's just about ''lying'' the new managers who don't know the players price(most of the times i see the buyers are new managers) and end wasting their money in players that aren't worth more than 10-20k
If a player is sold for more than what he's worth, just report the purchase and it'll be investigated. If it's really definitely overpriced, the GMs will act.
We have both said a lot of things that you are going to regret.