I find it strange that you would bring up the (possibly mythical) "20-year-old who knows everything about technology" in the same statement as "deep dives in college as a warning sign". In my, admittedly limited, experience, the big difference between someone with "a formal education with an expensive stamp" and someone without is breadth.
There are, as far as I've seen, very few "20-year-olds who know everything about technology", but there are plenty of 20-year-olds who know a great deal about some specific technology or technologies. And if that technology is what you need (note, not what you want), they're golden. And if by "startup/technology sector", you mean the "web startup sector", that's fairly likely. On the other hand, if it isn't, you may not be. If all you have is a hammer and a screwdriver, everything is going to look like a threaded nail.
There are, as far as I've seen, very few "20-year-olds who know everything about technology", but there are plenty of 20-year-olds who know a great deal about some specific technology or technologies. And if that technology is what you need (note, not what you want), they're golden. And if by "startup/technology sector", you mean the "web startup sector", that's fairly likely. On the other hand, if it isn't, you may not be. If all you have is a hammer and a screwdriver, everything is going to look like a threaded nail.