Thanks for your comment and additional info!
I'm not even necessarily advocating Zagg vs. other tempered glass protectors, just stating that they are different than a regular screen protector that only protects against scratches. They are designed to crack and (in my opinion) if they do and the screen doesn't, I take that as a win!
I don't remember where, but at one point had seen some videos showing screens being impacted with various objects both with and without different screen protectors and it was eye-opening. I remember thinking "what did we do before these tempered glass screen protectors?"... The answer is: we had a lot more broken screens!
So I do think they are worth it when justifying cost of these (any brand really, not only Zagg) and there might be a difference amongst brands, but at this price-point the differences are negligible. For those that are a bit rougher on their devices Zagg might be a better option with the lifetime warranty, but for those that would only need a replacement given a "freak-accident" it might be better to get one of the cheaper ones that don't have a guarantee.
Sounds like it might have saved your screen once or twice (and if it's just once-- it's worth it, right?!)