No, you don't have to do that, you can effectively out a "reserve" on players - when you lost them type the number in and then list and it lists at that price. The player then needs to bid that as a minimum.
As for the level of RP's it's absolutely possible, I've made over 150k in one day before selling surplus players that I'd trained up, cayden, dropkicks etc etc were much more prolific than me! Think about it, how often does a top rated player under 29 get sold, and what do they go for (20k+) now where have they come from? It's someone religiously training an 18-21 yr old. It doesn't take much to do that, esp if you are on the game all the time chatting.
You just need to get smarter about what you are doing and stop moaning...