The problem, IMHO, is the fact that Chelski's infinite wealth is only skin-deep.
One day our Russian oil friend will get bored with Chelsea and move on to buying some F1 Racing team or something....
If I were a Chelsea fan, I would be pretty anxious about the fact that one über-wealthy post-commu-Russia-oil-nut one day came to England, bought the team with the most expensive name in the PL (face it, if there were a Mayfair-team, he would have bought that one...) and made it (=invested into) a champion.
He's waiting for the CL cup, and then probably get bored with going to Stanford Bridge and get interested in other sports.
Two years later Chelsea will probably be fighting to stay up.