I made, and released, miners that were several times faster than the best public one for XMR. I barely got anything in donations. Making the same mistake twice is called stupidity.
The trouble with selling the miner is that there is no way to protect the kernels from the person who buys it turning right around and giving them away
Of course - which is why I sell it to one large farmer for a high price. His own need to get a return on his investment stops him from sharing it - I can even offer him an exclusive deal, that is, I only sell it once, to him. I've seen what this community does to miners with fees - I'm not getting tricked that way.
Completely right decision.