When I was 12, I had a business making $2,000-$3,000 a month.
By 14, I was making more than my teachers.
And as a junior in high school, it was a full time business (see below for my monthly sales then).
After realizing there was a model that could scale better through selling brand name products on Amazon FBA - I switched my business model.
(see Online Retail Mastery)
But for years, I've leveraged eBay to make a tremendous income.