Drawing pets has made me thousands of dollars, and you don't have to be well established and you don't really have to even get your name out there. I barely advertise it online, but pets people talk to eachother, and if you can paint a horse, you can make a ton of money.
If porn is what you need to do, then that's none of my business, but the original post is about buying an ipad, they are not starving. For myself, I would lose my dayjob if people see me drawing porn art, it's not a thing that everyone can do, in fact I don't think most people can really get away with it, which is why they tend to draw it under a username.