Obviously this depends on where you are located. Such as if you live in an expensive place in the US or Canada, then its a lot more than in other countries. Also if you are young, middle age or older.
This do really depends on where you do live considering that fiat value and lifestyle status will really be different into each places.
Some do say that 10BTC would already be enough on securing their future but for some would be asking out 100's or thousands of btc.
In my part then i would say that 700-1000 would be enough to secure my future yet i can be having a savings and tending
to built lots of investment for future passive income and leveraging.
Thats too much even if you do live in 1st world countries. $20M would really be enough or too much already for most people but if you are really planning to have some lavish or extravagant life then this amount would
really be too much but we know that human beings are inborn greedy so it isnt surprising.
Why would go for less if you can go more. Right? In our lives we do only hope and wish for the best of things that will satisfy on what we do have in mind. Lots of money where you can buy all you want
and able to secure out your future and to your family.
For me 10 btc will be sufficient, its just a matter on how you gonna wisely spent those.