Don't they read the news? Because if I had bought that amount of coins a decade ago, I'm sure that I'd see out of curiosity how well it has gone. Since the paper wallet was in his closet, it means that he didn't care that much.
This is either a made up stories or an attempt to buy Bitcoin back when it's worth merely a buck and decided not to. It's "almost" impossible for someone who bought Bitcoin and totally forget about it when in the first place he had been hiding his paper wallet inside a closet for almost 10 years and then heard the news all over the television, in the internet, and literally everywhere about how Bitcoin has been booming since the late of 2017.
I doubt there were only a handful of ordinary people who had Bitcoin just before the price went over a hundred bucks and still holding up until now or sold in 2017 or earlier.