Betfair is a British gambling company founded in 2000. It operates the world's largest online betting exchange. Its product offering also includes sports betting, online casino, online poker, and online bingo.

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.