In canon, it sounded like some witches pretended to live ordinary lives, and others lived “off the grid” in the middle of nowhere. The same mix might happen with higher-order witches, with some attending Hogwarts, some pretending to be muggles, and others going unnoticed by anybody.
If there are an arbitrarily high number of witch-levels, then the limit is the earth’s population, not the magical population. But that’s only a potential limit, as witches of arbitrarily high level can support an arbitrarily high number of themselves on one planet (or go to other ones).
In canon, it sounded like some witches pretended to live ordinary lives, and others lived “off the grid” in the middle of nowhere. The same mix might happen with higher-order witches, with some attending Hogwarts, some pretending to be muggles, and others going unnoticed by anybody.
If there are an arbitrarily high number of witch-levels, then the limit is the earth’s population, not the magical population. But that’s only a potential limit, as witches of arbitrarily high level can support an arbitrarily high number of themselves on one planet (or go to other ones).