The main issue with smoking weed for a young person such as yourself, is the chance of being arrested.
If you get arrested then it'll go on your file in the public registry, when you try to get a job in the future your employers will look at this file and will notice that you've served time in jail for drug usage.
Your chances of ever getting a job will drop substantially, not because you did the drugs but simply because you went to jail at all, no matter the reason