If you don’t know what they are, I imagine you probably have seen them. Often, they portray themselves as cocky, mostly “straight-acting” guys who show off their feet while flipping off the camera. And they ask other guys to send them money.
It’s not to my taste, but I’m the first to say that if it turns you on, and it’s not doing damage to your personal life, then go for it. I suppose that for many, sending another guy your money is the lowest form of slavery and humiliation you can achieve, and may not be all that different from being told to do other tasks or engage in verbal humiliation.
I do caution, though, that if you do decide to engage in it, be sensible. If you are well off (financially speaking), spending a bit of money to a Cash Master may be a worthwhile activity to you. But if it comes to a point where it’s affecting your personal finances, or turns into an addiction, that could be a problem. Also watch that you’re not being flat out scammed in other ways, since you’re now giving them access to your accounts. Be sensible and safe.
It’s not something that I’d personally engage in any form. To me, it’s crossing a bit of a line. Getting into another person’s finances is affecting more areas of their lives other than kink, and some of those areas are pretty fundamental (food, rent/mortgage, gas, etc.). I think there are lots of other ways to humiliate a slave that don’t involve getting into their personal lives in that manner.