As an only child you have to play alone, most of your entertainment depends on how good your imagination is. You have to think of creative ways to play games that traditionally require 2 people. (Instead of playing catch you bounce a ball off a wall etc...) You also don't have anyone to ask for advice. (What's the best way to get cookies out of the kitchen after being told to go to bed etc...)
Well I think the same thing applies to your hustle. If you hustle alone you don't have anyone to help keep you motivated when things get rough. Nor will you have anyone to offer ideas, insight and advice that you may have never thought of. In short don't hustle alone. As the saying goes "Friends multiply joys and divide griefs." Good company IN your hustle will keep you ON your hustle.