It's already compulsory in a sense since a Bachelor's degrees no longer qualifies you for a good paying job. You almost need a post-graduate degree to get a high paying job, which is what people will need just to survive soon enough.

In an ideal world we'd provide free education so that everyone (from a tradesperson to an artist to a businessperson to a teacher to a lawyer or a doctor) would get the appropriate training and education to set them up to succeed in life, without their parents having to put up a second mortgage on the house. But, that's an ideal.

As far as the K-12 grades, I think education should be compulsory. It's more than what you learn in the classroom or in the books, it's what you learn from school itself- discipline, time management, social skills, etc. What are your thoughts?