Because school is important and not at all irrelevant.

Education is important, not school. So long as school is a means to receive education it is important. A lot of people don't think it is anymore.

It becomes irrelevant when you're ahead on all of your studies (or if a 6 hour day is completable by you in an hour).

I am in the group that took 1-2 yearly week long vacations in elementary school. Nothing was lost, since I just did the week of required work in half a day after returning from vacation.

How will people make money to be able to afford to do those things?

How does having more life experiences preclude someone from earning money? I'd go so far as to suggest that a more rounded "real-world" education improves their chances of making money.

We need to stop thinking of "education" as a monolithic school concept that produces worker bees through rote memorization and repetition.

How different do you think your life would be today if your parents pulled you out of 4th grade for a week in February to go skiing or to Disney or to see cousins?