This is actually quite shocking to me, especially with Bitcoin becoming a more and more used method of payment every day. Youd think also that with as many addresses the centralized exchanges or services like electrum generate also that this % of dormant Addy's would be way lower.
Man, if I had one of these addresses back in the day and lost the key, def woulda offed myself a long ass time ago. Probably what happened if some of these addresses did end up going dormant due to inability to access.. I couldn't continue living if I was one of those individuals, that's for sure