I'd like to point out that your original English sentence is ambiguous/figurative to some degree, which I feel is more obvious when inserting "on" instead of "through".
I've wasted so much time just scrolling on Instagram.
This could very literally mean that it took me a lot of time to perform the act of scrolling itself (e.g. if there is some malfunction that causes scrolling to be veeeery slow), but what I most likely actually want to say is that I aimlessly browsed the app, which happens to involve a lot of scrolling.
A verb that naturally (way more than "herumwischen" which sounds weird to me too) catches the second meaning in German is "(durch-/herum-)stöbern" (can be translated by "to browse"). It's a term that's also used for doing basically the same thing in a library, invoking the mental image of picking up a lot of things in short order and examining them only superficially, which I think is exactly what you want to express.
Thus I'd say:
Ich habe viel Zeit damit verschwendet, auf Instagram rumzustöbern.