My younger brother (who was a complete shithead when we were growing up) used to call me a "wanna-be nerd" because I rarely beat games as a teen. Honestly, the main problem was that I have a mild spatial learning disability (that's gotten better with age) related to my ADHD that meant I would often get lost as far as what I was supposed to do next. And until GameFaqs-- there wasn't much you could do about that.
Games that come to mind in that regard include Donkey Kong 64, Zelda OOT, Conkers Bad Fur Day, Metroid Prime, Psyconauts and Beyond Good and Evil (the later two of which I beat years later).
Things started to shift during the era of Xbox / Cube / PS2 because of GameFaqs and because game design shifted in a way that made A to Z more clear (I think that's why I loved the shit out of open worlds and their maps full of icons).
Remember beating Star Wars: Knights of the Old Republic, Second Sight, Half Life and the Conker's remaster (aka my favorite game of all time) in a two year span and realizing that the tide was turning. Now? I beat probably 80-90% of games I start so long as I like them.