from my research i found that 50% of btc have been lost and can never be recovered
50%, from what you get this number for lost
BTC?
Nobody can make an absolute calculation for lost
BTC, never can do this. What people are trying to do is estimating lost
BTC and because they only give you estimations which are not correct 100%.
You can use HODL waves for UTXO age distribution and make your estimations with a note that not all very old UTXOs like 5-years old, 9-years old were lost. They can still be woken up by owners anytime.
https://unchained.com/hodlwaves/https://www.lookintobitcoin.com/charts/hodl-waves/