You don't have to make a decision about being a "professional". That word, strictly speaking, means making your living at melee. I'm guessing at this stage in your life, making your living is not something you have to think about much. I think its an important distinction to make, because if, down the line, you became a "professional", just playing the game would only be part of what you do. Right now, the people making a living off of smash (and that's a very small number) have to stream, travel, practice constantly (I assume), do very detailed analysis, etc... There's a lot of things you would have to give up. There's not just a threshold of skill you achieve and then suddenly you become a professional.
However, if you enjoy playing and improving, then making a commitment to smash can be an awesome thing. I think its good to really delve into something (music, sports, art, smash, anything really) and really try to be excellent, the best you can be. That is something that most people never achieve, because they never really try.
All that to say: I think you should go for it, cause its a really beautiful game.