It has occurred to me that we could start to use the term bitcoinaire in the same way we use the term millionaire today. A millionaire is someone who has $1M net worth (assets minus liabilities). Let's say he has a $340k paid off house and $660k worth of mutual funds (and no debt).
The term millionaire has always been used as a reference, but it is obvious that purchasing power has changed. Someone with $1M of wealth in 1980 had much more purchasing power than a millionaire today. Still, the term millionaire is still a good reference for someone who has accumulated a decent net worth, is financially stable, and is better off than most in economic terms.
I will propose a frame of reference to be used as a basis for transferring it to the term bitconaire.
A person with $1M net worth can buy a decent house in a developed country and, at least on paper, could live off the return on their investments without touching the principal. So, an American with a $340k paid off house and $660k in mutual funds, has a good house and, in theory, could live if he got a 10% annual return on that $660k.
I've taken that house price because the U.S. median home price is $340,000.
As for the mutual funds, in 2019 the median household income in the USA was $65k. 10% of the $650k would be $65k.
So we can say that, to call someone a bitcoinaire, that person he would have to have enough bitcoin holdings to buy a mid-priced house in the USA and with the remainder he should have 10x the median household income. With this definition, we detach ourselves from the evolution of the price of the dollar or bitcoin. Today we still think in fiat terms but tomorrow Bitcoin may be the unit of account. Even Morgan Stanley recently stated that Bitcoin is Making Progress to Replace Dollar. I that happens, I think we won't be talking about millionaires any more but bitconaires.
At current price ($57.5k) I am sure there are some bitconaires in this forum with 17.3BTC or more.