Because the Quest 3 is another product, this is the pro version. The consumer version will get released later I guess, and probably with a price closer to the current Quest 2.
If there even is another consumer version. It sounds like Pro is Facebook's ultimate objective for monetizing this, and Quest 1/2 was just a beta test for them to perfect their tech.
It's the other way around - Quest Pro is the one testing new tech (mixed reality, face tracking, foveated rendering, self-tracking controllers). I imagine they're going to hone these features over the next couple of years and include them in the consumer models once there is better economics/proven product market fit.