Self-hosting has some inherent downsides that will never make it so easy that it completely outclasses the competition by cheap mass-hosters hosting the exact same thing for most people. You or I might enjoy fiddling with technical things or keeping our computers running 24/7 or setting up some workaround CGNAT or DualStack Lite so that computer is even reachable from the outside (or even have a physically stationary computer in the first place, lots of people carry laptops around instead or don't even have anything but a phone) but most people would much rather pay someone US$1 a month to do all that stuff for them.