Something else to consider about those "irretrievable" coins: they may not be permanently irretrievable. As technology progresses, it may eventually become feasible to brute force the keys in a reasonable amount of time (although I'm not exactly sure how this would work, so I could be wrong).
It's not and never will be. It's not a matter of technology. There is simply not enough energy in this solar system to brute force private keys, even in theory.
I wonder how many times humanity has claimed the impossible only to be surprised by a very rude awakening.
Let's modify that to, "Based upon our current understanding, we believe this will never happen."
Brute forcing *does* seem overwhelmingly infeasible (but NOT impossible as there is a known chance of a collision, and though this likelihood is unfathomably small, it's still there). But, there may be alternative methods to brute forcing we haven't considered. In *theory* an advanced quantum computer would contain all possible private key solutions -- an analogy of how such an advanced computer can be imagined is to think of a library that contains all books that ever have *and* that ever will be written, and that there simply needs to be a method to find the book you're looking for. Accordingly, it's not so much about solving for the correct answer, but rather removing everything that's unnecessary to leave only the correct answer. Take this with a grain a salt; I'm by no means an expert on the subject.
The Infinite Library does not exist, and quantum computers only exist in sci-fi novels. Let's discuss this when we have a working model.