> Mining asteroids makes no sense whatsoever with any currently imaginable practical tech, especially not economically.

With current tech, it's practical enough to extract rocks from a rock. We've already done this on a comet, which I think is much harder to do. With current economics, not practical to fund such an endeavor, even if it was to haul back an asteroid made of solid gold. Regardless, we're discussing the far future, rather than current state.

If raw materials (again, an unknown) continue to become more scarce, it's hard to say what economics might support extra-planetary resource collection. What's for sure, is mining Mars will be harder than mining asteroids for water or metals, et al.