A naive approach would be to take the current Bitcoin price times 10 and then divided by 12 divided by 50. That would currently get me to a little over a thousand USD monthly for 50 years, assuming the price remains identical to what it is now and ignoring any and all losses from selling the coins for fiat using Bisq. (Transaction fees, etc.)
That is, I would not be selling them all at once, but at most frequently once a month (or maybe once every quarter, if that's better), fixed to the $1000 USD amount which I've determined lasts for 50 years, which is how long I might still live (I'm 35 now). It's quite a depressing and surreal thought, me sitting there in five decades, as an elderly man, still launching Bisq on some kind of Windows 10 OS on my dusty old hardware from 2019, to sell some coins to pay for my rent, food, electricity and Internet...
But logically, the value of Bitcoin will keep increasing over time. So maybe I can dare to be as bold as to take out $2000 per month, which currently would last for only 25 years, but due to the increased price would still last for 50 years? But what then if the Bitcoin price doesn't go up, or even goes down? Or happens to be low each time I sell them on my schedule? Then I'll sit there in 25 years (or sooner), all broke. Obviously, I don't want that.
Either way, it's going to feel awful "burning" my BTC like this, watching my BTC amount slowly decrease to an eventual zero, but I've determined that all "lending" options are either just not available to me, or way too risky. I don't trust any such existing mechanism, that's for sure.
I'm trying to determine some sensible "model" or "expression" for this which takes into account the likely price fluctuations of Bitcoin, allowing me to not have to live so incredibly cheaply. (Where I live, those thousand bucks per month do not make for a grand life.)
If I had a reasonable algorithm/expression for this, I could keep calculating it (automated) every month to know how much money I can grab each time for this to still last for those 50 years. Do you have any tips or insight into a safe such expression that I should use?