This also got me wondered as to when Bitcoin price rises and experiencing new ATH every year, it had never happened like this before which absolutely, the calculation done by the OP can never be correct. Op's calculation is based on the fact that Bitcoin price always reached new ATH every year and such assumptions had never occurred and can never happen resulting it to be faulty.
That's based on his assumptions and that the price of Bitcoin will be high every year by 2036. It also shows something out of it that you should only have at least 0.8 BTC by that time and we've got plenty of time, a decade until we reach to that amount. While it's known from the forum that there are notable users here that have more than 1, 10 and even more than a hundred. They've got their own plans too and people should read what's suggested about JJG's thread. It's very insightful and can give some idea on how to plan your sale.