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I‘m 15 and have a rating of 2600... do you think I can become a GM?

Not if you keep asking questions like this!

DO IT! Don't ask other opinion !
Just do it!

If you wanna be a GM, DO IT!
If you wanna get rich, DO IT!
If you wanna buy a house, DO IT!
etc etc.
>I‘m 15 and have a rating of 2600

Lichess rating its like a gold medal in the Paralympics. It doesnt matter.

You need to earn FIDE rating. How much do you have?