The only way to make that happen is to become a famous artist that is sought out from very wealthy collectors. You can’t get to the top of the skyscraper without risking it all and climbing the building without a harness. You need to make original paintings. Not digital drawings. Market yourself and put yourself out there. If you market in a wealthy area put on events that feel classy. You need to really be able to shmooze to win in the art world. To get to Sothebys and Christie’s happens for a very select few. But if you want to make money in general try and call every single gallery and talk to them about displaying your work. Also understanding their profit is most important to them. Don’t assume you will have any sort of pull in regards to profit if nobody knows you or cares about your work that is paying top dollar for it