"a lot of money"
the various industries is extremely competitive. and there's no minimum wages online. don't quit that day job, relish it.
younger illustrators for example with skills, aren't going to understand their time is worth more than what they are commissioned for, driving the prices down for everyone. they have more time, they don't to pay bills, etc. so they can afford to do such things.
though it's not exactly the same, this 'saturation' is across all artistic industries. animation, music, writing, etc. the ones that are well paid, are the exception of rarity, they aren't the norm. your favorites anime, the animators whom worked on them are barely making by. some of the top webtoon creators are barely scraping it together. WebToon and Tapas and the various sites, they aren't design to make creators succeed, they are design to generate as much money as they can.
the 'best' way, is direct Patreon support or something similar, for whatever you may be creating. and even then. Don't quit your 9 to 5, that's just reality. It'd be a dream, but it's far fetch and most of us won't reach that.
the alternative and more realistic approach is getting picked up by an actual company and no longer freelance or create your own stuff. though still. it's quite saturated. but this is the most realistic approach I think.
to think that you can make money off of Tapas or Webtoon or any hosting website, is just. no. you have to understand the reality of the industries and the history of how much people are being paid. you'd have better luck becoming a YouTuber or Streamer, and that's a bit of humour, because those fields are also less than minimum wages for most. the ones you see well paid, are far far exceptions. keep your day job.