it would be very interesting to know how many of the failed projects are still listed at any exchange around the world. And how much money was burned?

I trust a good percentage of these were scam, not even designed to succeed at all. Many others, I assume did only focus on technology and had no valid use case in real world.

A significant part might have failed because they did not focus on the creation of an actual company, which incorporates far more than just creating a token and a whitepaper.