Some people have no interest in the subject of magic at all.
Some people come from cultures where magic is not valued.
Some people belong to religious groups that actively oppose magic.
If vegetables are so good for you, why doesn't everyone eat them?
If marijuana is so bad for you, why do so many people smoke it?
If war is so evil, why do so many people become soldiers?
If television is so attractive, why do so many people refuse to watch it?
The answer to all of these questions is this:
People have free will and they make choices consistent with their interests, desires, emotional states, skill-sets, and the circumstances which put them into convenient proximity or keep them at an inconvenient distance from with various mental concepts and physical objects.