Not "all", but most.
Investors went positively able-sugar over "dot coms" and threw obscene amounts of money into businesses with questionable business plans. It was if someone decided that the rules for business had simply disappeared (you know..........little things like "a company needs to actually turn a profit"). It was nuts; I was smack in the middle of it, and I kept advising my clients (I was a consultant at the time) to take heed ("......don't go stupid on me here; understand that you MUST have a business plan that "closes"; don't think you'll strike it rich by having an Internet focus only...").
It gives me zero pleasure to say that I saw it coming.......big time. When the balloon burst and tens of thousands were bounced out of work (most with huge debts), I didn't blink an eye, much as I felt for 'em.
Still...........I think the whole misnamed "dot bomb" thing was healthy. It separated the wheat from the chaff and made the world of online business grow up fast. e-commerce didn't go away; far from it. It morphed quickly into a real business model......and that sorely needed to happen.