Some people just aren't able to really do the learning grind for end game stuff for a lot of different reasons. Schedule can be too difficult to join a steady raid group, health problems that make long grinding sessions difficult, lack of ability, lack of interest in raiding, or just don't have the time to learn content before it becomes obsolete. I've never paid for a clear on any games, I rather enjoy the whole learning/wiping/watching people rage like crazy and tell everyone they're pieces of *&#$, but I can definitely understand why some people do pay for them. Crafters end up with hundreds of millions of gil and nothing to spend it on anyway, so if they know they will never be able to clear something without paying for it, why not?