They are usually only a few bucks on eBay or Amazon and they have saved my screen twice now where the protective glass screen cracked when dropped but the original screen underneath was protected. Worth their weight in gold!
But how do you know it protected? Maybe your screen would’ve been fine unprotected anyway. Maybe the protector is just cheap plastic/glass design to crack at a modest impact so you are suckered into buying more protectors. I’d be interested in side by side identical testing, one with protector and one without. Does anyone know if this has been done anywhere? Maybe consumer reports or the like?
Purely from an empirical observation basis I feel I have paid the insurance deductibles on enough cracked screen smartphones for myself and my 2 kids over time that I have a pretty good handle on if they are being protected. My adult daughter is absolutely brutal with electronics and smartphones used to last about a year before “something” would happen and I would be pulling out the credit card. Since I went the Otterbox Commuter case + glass screen protector route a few years ago I have replaced several cracked and battered Otterbox cases and several protective screens but the protected phones have remained in good shape.