You might wish to invest in a chain clean kit and some dry lube and try to keep the moving parts a little more grit-free.

I have worn out hubs and bottom brackets, worn away chains, and worn out cogs, as well as completely ruined derailers before. It all goes with grit in the moving parts.

Now I bring the bikes in the house and put them in the tub, use the little silly plastic box to clean the chain, and hose the whole thing down regularly.

Hubs and bottom brackets need a lot of TLC, dirty BBs can ruin the inner workings of the bike. Learning to service them isn't too hard, you just need someplace to work ( newspaper on a kitchen floor is plenty ), some rags, some solvent, white lithium grease or bearing grease, and patience.

I use Lock Ease graphite suspension, which is graphite in a petroleum solution to help the graphite penetrate, on my chain.
White lithium grease in the bearing races, I can easily see wear and dirt as it changes the color of the grease.
Toothbrush for cleaning hard to get to places.

It's frustrating, but it does seem like reasonable wear to my distant perceptions.