Zero percent market share
If you have a million Twitter followers, that means that 99.9% of the people on Twitter are ignoring you, which, with a little rounding, means you have 0%.
If you write a book and it sells a million copies, it will be one of the bestselling books of the year. It will also reach far fewer than 1% of the country’s population, never mind the world.
There are very few things that ever rise to 1% of the market. You don’t need everyone, in fact, the act of chasing everyone is probably keeping you from reaching anyone.
Zero (rounded) is enough.