In 2 or 3 seasons he is not going to be able to afford the guys salary. This means he is either going to have to stop training him or sell him.
In 2-3 seasons he will be able to afford the guys salary just as easily as a lower potential guy. we both know salary is not affected by potential. He should be able to easily climb to D IV over the next season or two in which he could easily afford a salary up to 100k. As he climbs more divisions he will be able to afford a higher salary and not have to regret not having a higher potential player. We get so little training in this game you have to concentrate it on 2-3 players in order to maximize your benefit.
If he sells him, he will probably get less money for him than he would now.
Wrong, he would in fact get much more money. A HOF potential player w/ 2-3 seasons single position training would garner a lot higher bids than a rookie.
If you don't want to buy players, then he can just as easily build up his arena if he is already confident of promoting.
He could easily build his arena off the revenues he earns, its not like you need to drop hundreds of thousands into your arena at DV
You say he could keep training him forever, but the fact is he can't, as soon as his salary gets expensive he will have to stop.
100% wrong. I got Willis Lundy in the draft when I was in DV. Willis has been single position trained since then and is now an elite guard. His salary is easily affordable for my team and he is the only reason I have climbed to D3 almost making it to DII last season.