This has been rehashed so many times.
I don't think anyone really believes their tackle will make them a better angler by any measurable amount. At least not those past the raw-beginner stages of the sport. What I think happens is that a lot of guys get discouraged with the learning process, or can't devote enough time and effort to it, or are just impatient and in their enthusiasm, decide that if they can't improve their skill, they can improve their gear. I think it's mostly a subconscious process too. Say you want to learn how to czech nymph, or you want to start fishing big streamers. You aren't going get good at it it one or two trips, but you can buy the same gear as all the experts use and have it tomorrow. There's certainty to it. it's tangible. It feels like your are making progress even though the improvement of your situation is incredibly insignificant.