~snip~
I am not sure if 20 BTC is going to be enough to supplement the cashflow of any person, even though it seems that something like 100 BTC right now would be enough - yet of course, devil is in the details in regards to how much we need and when we need it..
~snip~
Anyway, of course, money management.. and of course no guarantees.. and surely by the time we start to get into our 50s or later, then it would seem that many of us shoudl have already created and maintained some investment portfolio that goes beyond merely having BTC and perhaps taking our other income sources, whether social security, pension, 401ks and/or other sources like that with a grain of salt... but still the various uncertain sources of income likely have greater than zero present value.. unless you really are assigning high values to Armagaeddon scenarios.
Having said all that I totally appreciate you, if everyone was as smart as you, think Bitcoin would already be a real currency in many countries. But although I'm not entirely sure, hope that Bitcoin will one day become a real currency like gold was a currency in the primitive days, I think it will be, even though we know that every currency is unstable. But the difference is that the area of change is a little more or less and it is also true that it is not right to judge Bitcoin by all kinds of differences.
Finally, it can be said that every person needs to have a deep understanding of Bitcoin like you(That is the Example of Knowledge), so that Bitcoin can become more prosperous in the world.