My guess is a lot of pilots are satisfied with mediocrity because anything higher is just to difficult for them.
You could level that at most activities though, driving being one of them. There's an element of being good enough to do something with reasonable safety and wanting to be better at something for the sake of being better at it. Personally I like to be good at what I do. It probably makes me no safer than the guy who flies once a month to the same local bacon butty place but we really have no right to criticise that. The same guy may get great pleasure from it and be as safe as houses.
It's the same as a guy who makes a table. One guy bolts four 4x4 pieces of fence post to a slab of pine. He has a table and it will stand for a hundred years. It wouldn't be the table that I would make and you or I may criticise the shoddy nature of it and lack of finesse but his would still function as a table. Same with pilots. How good do you have to be? I'm only driven to be better at something because that's my personality type I suppose. If I can put an a/c within 50' of where I want it to be I'll want to put it within 25' next time. It's not really making me any safer because I'm never going to land on a spit of gravel in the Canadian tundra, it's just my desire to be good at something. Other people are different, good enough does for them.