Doesn't have anything to do with updates, but yeah hardware might fail over time. Thats a risk you gotta take.

Yeah thats partially true, but many cricital issues get patches with Google Play Protect Updates. Also at least I'm not aware of any big hacks that happened on old Android Versions.

True yes, but id say 99% of Apps still support Android 9 which is 5 years old.

No they don't Software becomes more demanding and so things overall feel slower. There can be cases where stuff like the battery can't supply the voltage and thus the CPU can't reach its peak Clockspeed, but thats pretty rare

No it became much easier since all phones now are made with glass or plastic. They now can be opened from the back which means you never have to touch the Display - the most fragile part.

Yes thats an issue but if your phone was somewhat popular you can still easily get them. I for example replaced my Galaxy S6's screen protector last year. Still was able to easily buy one.