It takes a LOT of time and a LOT of dedication and a LOT of money to get really good. By really good I mean good enough to consistently make money. Sure, you can make some nice spending cash by going to the nearby places and cleaning out the suckers every weekend, but to do well against good players is a whole other level.
You will lose a lot of money, and you'll have terrible slumps... but it's all part of the learning process. Read books on the game written by experts, play a ton of hands, but not garbage hands online for free, all you learn there is bad habits.
Honestly the hardest part is realizing that no matter how good you are at playing a certain "style", you will never be really really good until you can play all "styles". Good players understand the dynamics of the table and shift gears into different styles all the time.