No money to be made in Prog. Just throwing it out there.
There's little money to be made in most genres nowadays. Unless you're a big name like Taylor Swift, Chance the Rapper, or Marshmello, you're probably not going to be making a whole lot of money off of album sales, streaming, or touring. There was a video Misha Mansoor did with Rick Beato where he talked about this and said that he barely breaks even from touring and album sales. Most of his money comes from sponsorships, teaching, and things like that. Album and song sales are declining in every genre and even big pop artists (aside from Taylor Swift) are having trouble filling venues and selling tickets. Prog/metal being kinda niche just makes it a lot worse for them.
Every genre is over-saturated at this point because it's getting easier and easier to make music than it ever was. Great-looking music videos can be shot on iPhones now, anyone with a decent laptop can get a DAW and start producing and recording music, and equipment is getting cheaper and cheaper. Services like Distrokid, CDBaby, and Tunecore let you blast your music into every online service imaginable. You can even post music directly to things like YouTube, SoundCloud, NoiseTrade, and BandCamp. People can even pay you directly through Patreon. The barrier to entry in the music industry has lowered so much in the last decade it's let ANYONE start making music. This lets a lot of great artists (like Chance the Rapper or Lindsey Stirling) that would've gotten lost otherwise get big, but it also let a lot of crap get through the flood gates.
It doesn't help prog's case that it's a bit behind the times with all of this. Most prog music videos are quite frankly uninteresting and poorly produced in a time when the music video is actually important. The only prog band I can think of that actually uses Patreon is Ne Obliviscaris. A lot of big prog artists don't even have their music on streaming services (like Neal Morse, early Spock's Beard, and Tool). A lot of prog artists are stuck in the past and--quite ironically--not embracing all the progress that's been happening in the music industry. People like Steven Wilson are often outright hypercritical of modern music, which certainly doesn't help matters. Doesn't help that a lot of the fans support this behavior. :v
That said, there are a LOT of good progressive bands that have come out in the last decade or so. Ne Obliviscaris, iamthemorning, The Anchoress, The Dear Hunter, Haken, Animals as Leaders, Diablo Swing Orchestra, The Algorithm...There's a lot of cool new things being done in rock/metal music right now if you know how and where to look for it. These bands aren't as big as say DT or PT sure, but they're just starting out. Most of the contemporary big prog bands we know didn't start big. They grew over the years. The recent bands just haven't had much time to do that yet.
tl;dr: the music industry has a whole is going through drastic changes and prog has been slow to keep up with the times, there's a lower barrier to entry which lets a lot of crappy bands in, little money in prog, and there are good prog bands that just haven't grown big yet.