When looking at getting to a professional level and making a career out of piano, I would first of all carefully consider the following:
1) Do you love doing the work needed to get to a professional level for the amount of time that is needed?
I think the OP's question has been answered pretty fully, so allow me to indulge in a bit of fantasy.
I think it's probably false that anyone "gets to" a "professional level" and then is allowed to play.
It seems rather to me that the very rare star soloists are backed up by a mechanism that is fairly well tuned. Starting with "their" manager, and continuing down the line to PR people and record label A&R people, down to Instgram influencers and whatever else. Nothing wrong with that: just the way it is.
I've known a lot of piano men and women, who are without doubt professionals, but to a man and woman, they've been supported by institutions, chiefly universities. That's just in "classical" legit music, as performers only. They can concertize on their own time, and when the university requires, but their work is typically not a tenure track in performance, unless one is a scholar as well as a mere performer, with research, publications, and contributions to professional colloquia to back it up. Yes, there are obviously exceptions, but it's not a rosy picture for academics in the US for the past thirty years or so, and likely more.
As well as composers, but the doctoral compositions I've heard, and I say also with love, by friends of mine as well, well...nobody's going to be performing what I've heard, as grandiose and swell the pieces may have sounded, so no Kronos Quartet covering blah-blah in 11/16 time from string quartet for office chair, marimba, candied necklaces, and prepared piano, or whatever.
Another way to think of it is: who are the "independent" wealthy people in music? A pop songwriter, or a producer who is able to get mechanical rights.
Although hard-core studio musicians existed then and exist today, in all realms of music, AIUI, it's mostly for wages, with some minimums negotiable by one's reputation. Hired gun.
I don't really know what it means to be a "professional": there are some board certifications, and a few memberships, but all I understand is that from the moment you get paid to play, then you're a pro. Maybe not a very good one, but there are professional dentists or plumbers or lawyers who aren't that great either.
More or less, can you compute your taxes correctly, or hire someone to do so, and can you show up and play? And possibly keep your employees (aka "bandmates") in line? If so, that's a professional. Show up, have the right gear in working order, don't bother the guests, and play the fricking music. Pay out after loading up afterwards, and that's it.
Not a very difficult hurdle.
Who are these "professional pianists"? They're probably playing Pachelbel's "canon," or some Tin-Pan Alley standard or whatever, or at some hootnenany in a holler for spare change.
Careful what you wish for. For me, I like it, but it's a "gig economy," so whatever
pays plays plays, pays. That's better.
Let's be real: if you look at the lives of composers and pianists, it's always been like that It's a constant struggle. Even for very famous pianists and composers.
In addition to building your private library of scores and analyses, I'd get a good set of maps and become very good at driving a cab.
Do you want to spend a hundred hours each week hustling every single job you can, and keeping in close contact with people you might personally despise, for what amounts to table scraps, every week, every day, for the rest of your life until you die?
If so, then good luck.