Somehow until this very moment i had never contemplated the fact that cacti have normal roots. That if you dug up a cactus you'd find Regular Plant Roots under it
the thing about this is that no answer feels satisfactory to me. like the idea of the cactus just continuing into the ground in the same shape is obviously wrong. the idea of it just not burrowing into the ground is stupid. but the idea of it having normal-ass roots is also deeply unsettling. there is no possible way the cactus could exist without there being something strange at its foundation