If they are seeing you that regularly it's because they can't keep a GF. They are assholes, socially inept, unhappy in their life, and unable to have any long term contact with someone unless they pay for it.
I think you're wrong about assholes. Assholes can easily form long-term social contracts, though such contracts are often abusive.
I think the people the OP is referring to are simply socially inept (as you also noted). They may have an illness (such as Asperger's) that renders them unable to form strong social bonds with most people. And so they are lacking a very significant part of life. Paying for social interaction is a way for them to fill that necessity. The problem is that they become chained to that, as they're not getting it anywhere else. Obviously this leads to difficulties as SPs are often highly desirable and therefore have their social needs met elsewhere, and so they don't form the same bond with their clients. No relationship is more toxic than where one party is absolutely dependent and the other party is independent. Obviously such an arrangement leads to a dissonance of respect, and feelings of ill will on both sides. Over time the relationship breaks down and gets increasingly nasty.
I don't look down on such people because in a lot of cases I believe they suffer from mental illness. But I do feel sorry for them and for the SPs that get involved with them. It's a shitty deal all around.
I would recommend that SPs don't mix business with personal interaction. Make it clear with clients that the transaction is purely business. If they have a problem with that, don't see them.
On the flip side, if you do develop a personal relationship with them, cut off the business side of things. See them off-the-clock and only then.
Mixing the two causes problems in a lot of cases, and the blame falls with both the client and the SP.
I've been in the hobby for awhile now and know that some SPs will purposefully see you off the clock in order to make you feel "special" so that you'll spend more money on them. I find this predatory, and I can especially see why socially inept people would find themselves in trouble.
I've also been lucky enough to form some lasting bonds with SPs that exist outside of the industry, as evidenced by continued interaction when the money flow stops.
That said, even I have had difficulty distinguishing between the two at times, so how many fall into that trap, then have misgivings about it and decide to lash out?
I don't know the OP in this case, but how innocent is she in this situation? She admits that money was a factor and she didn't want to lose what I'd call "whales", and so continued her relationship with them despite knowing things were off. What worries me the most is that she says she tries to maintain "friendships" with all of them, which tells me she is absolutely crossing the line between business and personal.
As with most situations, both parties probably bear some responsibility, and as is often the case, neither party will admit their own.