Many reasonable points, but misses the biggest lesson you MUST learn to have a chance of being successful at anything.
The lesson is simple. It is that you know nothing, and nobody else does either.
On the note of cofounders... I can't understand why more people don't end up in business with childhood friends. Met my cofounder aged 12. Started our first business at 13. Then 14, 15, 16... Then 22 - and that one stuck - 31 now, both in years and headcount. Trust isn't something we even think about. It just is.