Also there isn't any cost to selling a new key after the software is made.
FL also wouldn't have astronomical valuations of 1bn or whatever 23 made it to.
Even in third world scenarios, it you secure grant of government funding, anyone could become customers.
What actually went wrong here is not a matter of growth but failure to attain what should have become a sustainable business model.
but the difference between food and 23andme, beyond the obvious necessity v curiosity, is that 23andme is a 1 time purchase. once someone has seen their results, they've extracted all the value and have no reason to buy anything else.