In summary, to make money money on Betfair you MUST do two things. First, suck up every bit of knowledge that is available. Build up a small list of 'edges' to deploy when the time is right, understand that each of them has their place. However, the Betfair markets dictate when you will be able to use them.
For this reason alone, Betfair has no reason to ban or close your account when you should win. This is what Betfair first became famous for; peer-to-peer betting. Whilst the Exchange account won't be closed for winning, there is an additional commission rate.