Personally I have always avoid to take any amount in exchanges.
You friend at least he has been luck enough to leave these coins in a decent exchange.
In these years it was full of scam exchanges

and a lot of people had trouble even for trivial amount.
but if you think these are crazy increase of value. people thinks (errating) that only people that bougt btc for few cents could have decent profit.
Meanwhile even few years ago it was already possible save and get an impressive increase.
Yea, he was lucky that he used Coinbase. Perhaps, I believe that amount of money was something that he can afford to lose and that was why he didn't bother if the funds get missing or not. Since bitcoin has hit six digits was why the owner of the funds picked interest to check his account. If you read the OP, the owner couldn't have access due to some important data that he forgot. Bitcoin has the power law to increase in value exponentially overtime and early investors are proud of jumping into the train early.