Earlier quoted context omitted.
The supply of capital-B Bitcoin is 21M, but at any time, anyone can create Bitcoin2, which is an exact clone of Bitcoin but with a fresh chain. Any Bitcoin2 token has exactly the same utility as a Bitcoin token in principle - the only difference is that, for now at least, lots of people are mining Bitcoin and no one is mining Bitcoin2. If there comes a day when a lot of people think there should be 42M bitcoins, inst…
yes but the beauty is that, due to the lack of a central authority, the game theory of the situation virtually ensures that no one would ever do that — that is, take bitcoin2 seriously
It's probably unlikely that an enfranchised bitcoin user would be incentivized to jump to a newborn chain, but I don't think it's the case that a new user is always incentivized to adopt the existing chain. As the price of bitcoin increases, and the remaining coins to be issued decreases, a new chain becomes more attractive for new users.