Anyone can become a wizard. They just have to create their own fully realized language to speak their commands in.

Anyone can write down their spells into spellbooks. They just have to create their own unique script to do it in.

The greatest of spells require the greatest of languages. The magician who moves mountains speaks a tongue that has all the depth of a language with history behind it, and all the limits and weirdness of a language spoken by millions of humans, and all the resonance of a great literary tradition. The magician who moves mountains is speaking masterpieces of oratory in words that no one else can ever understand.

Truly great magicians sing their spells, in a musical tradition that only they know.

If a power thou wouldst be
thou must know what’s known to only thee,
Write thou in letters none else can see

Speak thy words in an unspoken tongue,
Sing the songs that cannot be sung,
All from thine own heart painfully wrung.

it is almost impossible for a magician to teach his creation to someone else. The most common result, when he succeeds, is that the magician loses his power and the learner gains none. Less common, much less common, the learner becomes a wizard and the teacher loses his wizardry.

Everyone wants to be a magician. Everyone admires magicians. Everyone admires power, of course, and wealth, and status, and magicians have those things. But they also admire the inner achievement, the greatness in creation of which the magic is an outward sign.

There is a cursed land where magic doesn’t work. The people who live there can never do great magic or even small. Instead from year to year they learn new techniques and the ones that work they pass down to their children. They work together, since no one of them can do anything monumental on their own. They experiment, they fail, they succeed, and they learn and grow. They accumulate a little more wisdom every generation and pass it on to the next. Now they fly gleaming rockets to the Moon.