The dot com crash left behind physical assets, notably quite a few undersea cables. The thought was that it was going to be insatiable market, and a huge investment could be amortized reasonably quickly by charging then-current datacomms rates.

After the crash, those assets were purchased at less than pennies on the dollar. The new owners had a much tinier investment to amortize, so they could lower rates (IMO rather spectacularly). This had no small influence on global interconnectedness (e.g. inexpensive trans-Pacific VOIP phone calls); if you're looking for something to blame all the robocalls you've been getting, this is a good candidate.

That said, I expect blockchain to continue. There's a lot to be said for an unalterable distributed record in some areas (e.g., stock certificate ownership), but I expect that to be limited.