It sounds as if he is invested in more cryptocurrencies than just Bitcoin. It’s just bitcoin is what people have heard of so it goes in the headline.
I agree the time scale sounds a bit optimistic (but then the whole thing sounds barmy to me) but I suppose it’s a trade off between how long his money will lasts versus when the bitcoin rapture hits.
I can see someone who sold his house and business easily having enough money to sit around doing nothing for that sort of period without leaving him penniless at the end of it.
That does seem to be how he managed to persuade his wife to agree to it 
