I just picked the only 5* eighteen year old in my team and went to personal trainer, and it would take 912 tokens for him to reach 8 stars. A 19 year old 5* in my team would take 976 tokens to reach 8*.
I think you are missing the point here though. It doesn't really matter if he's spending $2000 or $5000 a month, it's still beyond the imagination of almost all of us that someone could do it.
But, in the way our capitalist Global society is set up, there are people with the disposable wealth to be able to make it possible.
I'm just saying that maybe he is one of them, rather than a 'cheat'. A teenager with a $20,000 a month allowance who wastes a chunk of it on Facebook games.