What aspect of financial challenges are you expecting? Is it negative or positive growth because there is no guarantee with being a professional gambler. No doubt that you would also be making some profit but he will also be losing big because he will have to stake higher. I believe maybe streamers can have probably a steady outcome either they are in collaboration with the casino but to be a independent professional gambler doesn't have a guarantee of financial break through.
Challenges of becoming broke.
I don't really believe someone could consistently make a living out of purely gambling or betting on a specific casino, because no matter how good or how pro you are with Poker and other table card games, there are always gonna be a person who's better than you or equally as good as you, not today but maybe tomorrow. You win some, but most of us have lost more. So, in order for someone to make gains consistently he needs to do something like these streamers do. Yeah, I'm talking about referrals and endorsements, get paid to invite more users while you're actively gambling with your own money.
What people misunderstand is that they think a professional gambler is someone who just gambles and earns money through it and is living a life through the earnings of gambling alone, which isn't true. As you said, a professional gambler might just be gambling, but it's not that they are always winning and never losing a cent to the casino, but it's just that they get endorsements, they promote platforms, and get paid for that, they refer people and earn affiliate commission on that, and there are a bunch of other things that they do to earn money.
So, reality check for some people: professional gamblers lose as well, they don't have a crystal ball that tells them the outcome of every single bet before they even make it only to get it correct.
However, that is about gambling games, but if we talk about sports betting, there can be people in sports betting who can make money without having to do anything else because they deeply understand the sport that they are betting on, and the teams and players involved as well.