Obviously, you are making the assumption that you have everything that it takes to become the next Maria Sharapova. I am pretty certain it's not true (
I've never seen you but I am sure she has nicer legs), plus it's important not to discount the value of luck along the way to the great success.
On topic now

First of all, it's very hard to separate "trading" from "investing" and any cutoff will be arbitrary. If you go down the passive vs active road, there is value to both and it's worth combining them if you have the expertise and the time. Second of all, active investing/trading naturally incorporates frictions and those things add up very quickly (btw, one of the arguments against robe-advising services like Betterment is the transaction costs).