concrete can be crushed and reused as part of the agregate mix, which is probably exactly what happened to it. waste not want not, right?

In any case, if it wasn’t a scumbag flipper, then it was probably the contractors using the pressure of the listing to force her to accept the first not-actually-low-ball offer that comes along. (and then all the sundry other bullshit contractors pull to inflate the price of the job)