I didn't "go back to" a non-e-bike but I did reincorporate one into my riding patterns.
Long story short, after riding the ebike exclusively for about 16 months, I discovered last summer that I still owned my original 1990's Bianchi (I had developed a clearly-incorrect memory of selling it at a yard sale, years earlier.) That Bianchi was the very same bike that had defeated me and turned me off of biking back in my early 20's; I never rode it enough then, and when I did, I'd way over-do it every time, ending the very few rides I took, always in misery, eventually giving up on biking entirely.
When I found it tucked away in storage last summer, I had just started contemplating buying a non-e-bike to serve as a back-up should the ebike go into the shop for a repair... (that had just happened; while waiting for a part, I lost 27 days of summer biking.)
So I got the Bianchi fixed up instead of buying a new one, and to my delight found that I could ride it like a champ now, having built up some strength and stamina on the ebike. In fact, by that time, I'd taken to always riding my ebike in the lowest assist level (or no assist) specifically to get more of a workout from my rides... So getting on the Bianchi, very close to being half the weight of the ebike, was like jumping on a balloon -- it was more enjoyable and nimble to ride than my ebike (at least, in the lowest assist I'd become accustomed to.)
So now, I alternate between them... a few rides in a row on the Bianchi, then a few rides in a row on the ebike -- or, an every other day trade off, etc.