I found the imprecision of this sentence kind of funny, just makes me think of weed:
"Lütke enjoyed selling—as a boy in school, he’d made some money buying items in bulk and selling them at a mark-up to other school kids."
"Lütke enjoyed selling—as a boy in school, he’d made some money buying items in bulk and selling them at a mark-up to other school kids."
That line just made me think of the guys our our middle school who would buy up bulk soda and sell them for $1 or $2. But getting in on toy/widget fads is much smarter, though with a higher risk of the fad blowing over while you had money sitting in inventory.