It's OK to buy it, if you somehow loose your account (get banned) , you loose money. Those who have build up their account from scratch to reach Member won't risk it (if of course they didn't bought it on the black market) .
The forum makes some profit so that's good.

P. S.  Thinking about it, it actually reduces the need to buy a developed member account for high price when you can officially buy the same functionalities cheeper and helping the forum in the same time