You've got 'payment for services rendered' confused with 'donations'.
There is a difference.
Actually, there is a distinction without a difference. In either model, when the customers go away so does the money. When that happens, the owner better figure out a way to attract more customers, or reduce the expenses. Business 101.
To your point, why donate to a cause that doesn't support you? For years the bannings have occured, it is clear to many that at any time this place will pull support from loyal posters.