Most of the people you encounter in online casinos are just playing for fun.  It’s a hobby, something people look forward to doing after a long day at work or after the kids go to sleep.  However, there are a few players who have been playing long enough and have learned enough about the games to make a living off of them.
Deciding to be a professional gambler has obvious risks.  Before quitting your day job, you need to make sure this is actually a viable option for you.  Winning a few poker hands one night doesn’t necessarily mean you will continue to win for the rest of your life.  You need to make sure you have done your research, learned the tricks, and can play well enough to have more money than you started with at the end of this endeavour.

Not only that, you need to have enough money to start with.  You cannot hope to earn money in the long run in you are betting more than you can afford to lose. If you cannot safely bet on the $10/$20 poker games, you will still need a part-time job until you can play at this level.  Even playing the $10/$20 tables, you cannot hope to make more than $50k a year.  You are not likely to get rich, which is the dream of most poker players.  Instead, you will likely be playing just to pay the bills.  

By sacrificing a few luxuries to save money in your everyday life, you might be able to save enough money to play at the bigger tables.  Moving up to the $20/$40 bracket will allow the serious player to make a decent living.  If you can continue to save enough money to work your way up through the tables, you can eventually make $240k a year at the $200/$400 tables.  However, in order to make it to this level you need to have an immense amount of skill and a good work ethic, always making sure that you only play the tables you can play safely with your current income.  Many people do not have the patience to do this and take too many risks, which results in them loosing money in the long run.

Above all, when choosing this profession, you need to realise that online poker will now be your job, and not just your hobby.  Many people think that playing gambling games for a living would be the most enjoyable job they could possibly find - until they actually do it.  Spending long hours in front of the computer every day can make you get tired of your favourite games fairly quickly.  This leads people to take long “breaks” from playing throughout the day (since they are now their own boss), and if they’re not playing, they’re not making money. It’s true that being your own boss lets you work whatever hours you want, and take whatever vacations you want.  But if you cannot be responsible enough to make sure you are playing enough to make a decent income, this is not the job for you.