It really depends on how seriously you treat poker. For me, I think the biggest mistake is not setting a clear budget and just playing whenever you feel like it. As a hobby, poker can be pretty affordable if you stick to low stakes, home games, or occasional tournaments.
Some players might spend $20–$50 a month just for fun, while others who play regularly could spend a few hundred or more. The important thing is treating it like entertainment money, similar to going out, watching movies, or playing another hobby, and never using money that affects your daily life.
I also think the value isn't only in the money won or lost. A good poker hobby gives you competition, social interaction, and a chance to keep improving. As long as you enjoy the game and stay disciplined with your bankroll, it can be a great hobby.