If they purchase the accounts and sell them cheaper, they're losing money.
If I purchase 1000 accounts today at three steem each, that'll cost about $400. If the value of Steem rises, it still costs 3 STEEM to create a community account, but I could sell accounts for 2 Steem, and make a profit, because 2 STEEM then is worth more than the 3 STEEM were worth when the account was purchased. If steem was worth $5 each, $15 would be needed in order to create a community account, but I could sell accounts for $10. I could sell 40 of my 1000 accounts for $400, and still have 960 accounts to sell.
Do you see now how you're missing the point and just yelling at the clouds?
"But a set cost would fix that." Yes! And that's all I'm saying! LOL! Damn.