What you also need to consider is that Roman is a businessman, and at the end of the day it doesn't matter how much he spends on the club, and whether he will get bored of playing fantasy football he will always be a businessman, and being such isnt going to sell the club unless he is going to make a profit, or at the very least recoup the vast majority of his expenditure.
I don't like what RA has done at Chelsea, but at the end of the day its happened and he is slowly reducing his investment in the club. I honestly feel that they will reduce their £500m debt to something more managable and still be seen as a viable proposition should RA decide to sell in the future. Yet we are talking about a business plan that was touted around as taking 10 years to do so.
Manchester United are a very viable company, and I am pretty sure that their debt is almost as large as that of Chelsea's because of the huge financing of the Glazer's takeover. (no flaming on this bit, not seen the accounts)