I don't think you've understood the previous posts. Nobody is claiming that you are evil, immoral, or bad, or are doing anything illegal, by selling miles. The only thing people are trying to tell you is that it's against the T&Cs that the airlines have set and that the airlines have every right to set and enforce those T&Cs - that you have no legal entitlement to sell those miles without repercussion from the airlines.

Whether the people telling you that use CC or not, or whether they even sell their own miles, is entirely irrelevant. Nobody is telling you that what you're doing is wrong; all we're telling you is that your sense of entitlement to do so is misplaced, and that you have absolutely no legal recourse should an airline catch you and choose to penalize you by confiscating your miles and closing your account. You are free to sell your miles as you wish; you just can't complain if the airlines choose to enforce their T&Cs, that's all.