I just finished watching the video below by @philpa
How much Cardano (ADA) should you have?
Around the server room we utilize a very sparse formula for when asked that very question:
(45,000,000,000 (ADA Max Supply) / 21,000,000 (BTC Max Supply)) = 2,142.857143 ADA
With the above recipe you now know, relative to BTC, how much ADA you should have.
The formula is quite elegant and powerful in its simplicity.
Example:
At 0.07 USD x 2,142.857143 ADA = 150.00 USD
That’s right you can buy 1 BTC today (2018-09-12) for $150
Of course, 2,142.857143 ADA, is worth way more than one BTC but no one has learned of Cardano yet, so you have to start somewhere.
Added 2018-09-15
A Cardano holder just told me they are a Cardano millionaire because they have 1,250 ADA. When I asked how they came to that number they said they came across this post and substituted world millionaires for BTC.
(45,000,000,000 (ADA Max Supply) / 36,000,000 (Millionaires in the world)) = 1,250 ADA
They went on to tell me there are 7.5 billion people on the planet:
(45,000,000,000 (ADA Max Supply) / 7,500,000,000 (world population) = 6 ADA for every person.
I thought I would pass their thinking along.