5. Figure out how much money you need to be happy, lets say $120,000 a year. If that's the case then you would need to have $3M equivalent of crypto in order withdraw an upper limit 4% a year. This way you have your cake and eat it too.
That is a nice strategy and probably everybody's dream. Retire using your bitcoin stash. Unfortunately, most of us do not have sizable investments in crypto, and we may never get there.
Maybe you may try with other crypto as the OP suggest and not just bitcoin because other cryptocurrencies that are cheap today could rise during your retirement and so you can either mine or buy a sizeable stash down now.