According to the Business Insider story, he already cashed out once before, then regretted it because the value went up even further later.
To be honest, the OP makes it sound crazy but the linked story makes it seem much more understandable if not exactly rational.
He’s been speculating in various crypto-currencies for a while as well as having other business interests. His father was a professional footballer so I assume there’s a bit of money to start off with.
His father died not too long ago which prompted the usual life reassessment. The family sold up his business and went travelling.
Now they’re back they’ve rented themselves into a camp-site where (oh, horror) instead of having their own rooms, the three daughters have to share one room. In a chalet. So it’s not like he’s living out of a tent and it doesn’t sound as if all his assets are in Bitcoin or other cryptocurrencies.
He’s picked 2020 as an end-date for his little “drop-out” experience on the basis that he thinks bitcoin, etc. will be mainstream by then and his investments worth shed-loads. If not, he’ll do something else.