Something to think about...
While it's true that the more they pay someone the more rope that player will be given. However, there are many who reach the Major Leagues even though they didn't receive a large signing bonus.
If a player signs for a low amount of money, he is going to get a chance. I wouldn't worry about the guys who sign for half a million or more... There aren't enough of those types to stop you.
If you look at the typical lower level Minor League rosters you won't find many players who got $500,000 or more to sign. There's plenty of room for the guys who didn't get the big signing bonus. Most MLB clubs in any given year will have three or four players they draft and pay a lot of money. Most clubs will have at least two (entry level) leagues they play in. Sometimes the highest paid draft picks will even skip those levels. This leaves at least 50 roster spots from a pool of players that might include two or three that received $500,000 or more. Each club will have several minor league teams, the high priced guy ay a given position can’t be on every team. There’s plenty of room for those who didn’t receive a lot of money to shine.
There are places that show signing bonus’ paid to each player a MLB club drafts. At least, those who have received any substantial amount of money are listed. If they draft 50 players and sign some free agents (most for practically nothing) you will see the vast majority of players on the entry level rosters will be players who did not get a lot of money. When you’re in the batters box or on the mound, it doesn’t matter how much money you have in the bank. You do good things often enough and you will keep moving up and maybe get the big money in the end. As in all things, there is always some luck involved!
So in the end, if a player doesn't make it, it's not necessarily because how much they have invested in someone else. For the most part, I would say it's a bigger advantage for those players that a club has a large investment in, than it is a detriment to the rest of the players. All players have to produce in order to stay, they release those they’ve paid millions to. They just don’t release them as quickly.