Be aware of them being vulnerable though.
Like an addiction. They could be lonely, mentally compromised but wealthy.
Being manipulated into paying for it. But they haven't really got the money.
Don't be too quick to judge.
No one is putting a gun to their head to make them send money over to these people so I don't think it's reasonable to call it manipulation. The girls will stop showing interest as soon as the person stops sending them money because that's all they're after. They're in the business of making money not making some chumps feel like they have an eGirlfriend.
It takes about 30 seconds of self reflection. "Would this girl be giving me any attention if I wasn't throwing money at her?". in 99 cases out of a 100 the answer would be no but they've let themselves trick themselves into thinking if they spend enough money on a person they'll get something in the end.
This isn't subway or a coffee shop with a loyalty card guaranteeing you something after X amount of spends. Treat it like a strip club. You can spend your money but it's always looking but no touching. No matter how into you they act to get the transaction completed.
It's no different to therapy and therapists. I got along really well with who I had. We had a good relationship for a year or so, he knew how my brain worked and I opened up to him and told him things I wouldn't normally reveal to others. Once we got to a point we thought I was OK he said there was no need for any more sessions and once my work stopped paying for it, we never spoke again. Onlyfans is no different.