I concur, I had 140 btc 10 years ago. Sold it all when it reached $800, which I though was peak.

I doubt the guy who sold the 5000 btc pizzas still have them.

Has anyone ever estimated how many btc might be locked up in early adopter wallets who have since lost the passwords or the hard drive, etc?

That number will only ever increase - bitcoin not only fails to grow in size with productivity and population, it actually shrinks.

It's massively deflationary, which is a terrible thing for a currency.

Depends on Satoshi.

Take this guy

https://mobile.twitter.com/GregSchoen/status/702616488117616...

Who lamented making $400 instead of $13k back in 2011. Those coins would today be worth about $95m, but there's no way he'd have kept them -- same as the buy who bought the pizzas (or the guy who sold them)

This guy was bored of $14/coin, it wasn't moving

https://twitter.com/rockerest/status/91885405368098816?lang=...

So he took the loss (in July 2011 they were at a peak, jumping from 77 cents to $15 in 3 months)

Had someone found an old laptop with the coins, they'd have been looking for it in the 2017 craze (ala Big Bang Theory) and sold then.

Bitcoin is currently 3 times the peak in December 2017.