Profession, professional are better adjectives.
Like any profession, there are successful professionals and others who are not, and since it does not require a university degree or someone telling you you can't, obviously many try it.
You are name two bad examples, I'm not even going to go into details.
In the case of poker, there are many players who become professionals and like anything else you do, you get tired or simply the stress is so great that you change and don't do it 100%.
Close examples of ordinary people, as they say, started with $100 (it could be more less, an example) tournaments.
Juan Martín Pastor, you can search for his story, in fact you reminded me of his case, and by Googling again I could see that he is still active, and making money, but in a quick reading of the results I could read that in 2020, he almost retired.
But here you have a player who went from everyday life to being a poker professional, and he doesn't have many Neon ads. There are many like his case.
And, at the other extreme, there are more famous cases, Adrian Mateos, left university and at the age of 22 (+-) had already won his first million dollars and is currently a high roller, the lowest buyin is $10,000, but he frequently in Buyin 50k, 100k,200k tournaments.
That was another player who started with his own investment.
Now, the reality is that for these levels and to be consistent over years, talent and many hours of work are required.
That is to say, not everyone can have Moneymaker's story, his case is really surprising, he dedicated a couple of years to being a professional, and today he is out there, in some tournaments, mainly the wsop.
So, the reality is that you dedicate yourself to betting like any profession would be, but you must have a plan B, C, D