Aside from the insurance which is a big deal, the fact is most clubs would have never gotten started without the AMA helping find flying sites and the funding and publicity help they give. And many clubs wouldn't continue to exist without the AMA, not to mention the work they did in the past getting us our own set of frequencies and continue to do in establishing safety regulations and keeping politicians out of it. AMA also does a lot to establish uniform standards for competition and events, which even if you don't participate yourself, the hobby as a whole benefits from. You'll find that most serious hobbies have a national organization of some kind that does those same kinds of things, and most serious hobbyists see the value in the dues they pay.