It can be profitable in the long-term if:
1) You play poker and other card games where you play against others.
2) You are an expert in horse races.
3) You are an expert in some other sports, use crossbetting and find betting sites that don’t ban you when they realize you are a winner.
4) If you find errors in physical casino games. Like the roulette not being 100% completely flat and some numbers tending to appear more than others in the long term.
1) I don't look at poker as a luck game, rather skill game(88% skill over luck)
2) I never heard of such gambler.
3) Only profitable betting is arbitrage, but there is risk that you will be caught and site will ban you and take your money.
4) Now, that is against every casino rules. If you do that casino will probably close your account and take all your funds.
And this with roulette is nonsense. I can assure you game is 100% based on luck. There is no pattern.
1) I partially agree. I would say the % depends on the type of game you are playing.
2) I have.
3) In betting forums in my country I've seen people complaining of being banned from betting sites because they were having profits during a certain period of time.
4) No. It's not nonsense with roulette at all. You probably haven't heard of Pelayo's brothers, expert mathematicians, specialized in gambling. They were going around casinos all over the world and they realized that some roulettes have tiny imperfections so in the long term some numbers appeared more than others. They wrote the numbers that tend to appear more and when they knew what those were, they started betting. They became millionaires. When casinos realized what was happening, they banned them.
They took casinos to court because they were doing nothing illegal. They just observed roulettes and bet afterwards. I don’t know how that ended but I am pretty sure that at least the biggest casinos in the world have made sure that roulettes nowadays have no imperfections.
P.S: I have searched what happened in Court and Casinos were obliged to re-admit them. So, Casino’s rules can say whatever they want, if you realize there is an imperfection and start betting and making money thanks to that, they can’t ban you.