thats a really small percentage of the pro players.  95+% will never see an MLB contract.
the stat that only 90% of pro ball players make it to the bigs is misleading.  The vast, vast majority of them will only play in a few games before being sent back down.  And they are being payed AAA money the whole time.
Oh, and yes a player on a big league team has the best job in the world bar none.