How many bitcoins do you think have been lost forever?
I personally think its around 3 to 4 million.
Today it is unclear as to how much bitcoin was lost. It is unclear if they lost forever or they can still be retrieved. Here are the things we should consider or the datas that we must gather to have a computed amount of the bitcoin that was lost. According to this site
https://www.cryptocoinsnews.com/thousands-bitcoins-lost-time/ these are the things that we should consider:
1.Thrown away harddrives with bitcoins in it
2. no. of bitcoins burned
So if we can gather all the datas needed then we can establish a fact as to how much bitcoin or lost