One key point is that you will never run out of #bitcoin (or any asset) if you peel of 8% of your sats (or whatever asset) with each new year. Doing so is asymptotic. 

The fiat currency value of your bitcoin will be volatile, but will generally increase over time… likely materially, if the past performance is any guide.

If you don’t think this will substantially outperform a traditional finance-based annuity, then I probably can’t help you.
#bitcoin