Question on sports betting bankroll

I'm fairly new to sports betting. Started in late September with $100, and now i'm up to about $450 or so. I'd like to make a decent amount of money doing this. I do try to stick to the rules of only betting like 2 or 3 percent of your roll as 1 unit.

But my question is this: How much do most people, on average have in their bankroll ? I know, just like poker, it depends, but you can say, the guys that have at least $1k in a poker roll, do fairly well.


So that being said, if I was to be 'deemed' a successful sports better, how much money should I have in my roll, be it from winning it, or depositing ?