Calculus as taught in schools has no practical purpose though.

It's as if high schools taught "programming languages" by telling students the definition of variables, constants, and functions – and then left it at that, with no further elaboration and no actual exposure to programming.

I have a math degree and believe there is lots of value in teaching mathematics to the general public. But I've long been convinced that high school-level calculus is a tremendous waste of time. It's a random concept from advanced mathematics, dumbed down, robbed of its rigorous underpinnings, and placed in the school curriculum for largely historical reasons. Replacing calculus with basics of mathematical proofwriting would be far more beneficial.

I'd recommend replacing calculus (and several of its precursor classes) with something more practical. A year of finance, or understanding numbers in the news (poll results, statistical significance, interest rates, numbers like market indices and marginal tax rates, etc.)

Right now we teach proofwriting in the context of a geometry class. It's a good thing that students learn to understand the basic concept of proofs, but it seems odd that we're literally re-using the curriculum from ancient Greece. I'd love to see it replaced with a class designed from the ground up for proofs as they are actually done today.

Students should absolutely keep learning mathematics, as much as they can handle, but the entire curriculum (especially after basic algebra) could use reconsideration. Calculus is still crucial on a track for mathematicians and scientists, but most students don't need it and their time would be better spent elsewhere.