please don't shoot me for the ultra noob bike question

The big ring will wear faster than the little ring. Chain wear is a function of mileage/maintenance/etc.

Thanks djastroman, that was kinda my theory of it.

thanks for all the responses everyone, I kinda figured this answer. Anything you use more will wear faster etc. I didn't understand his logic though and I figured this response.

The big ring will wear slower because the wear is distributed across more teeth.  That being said chainrings last years, so use the gearing that works for you.

As far as chains go, they don't wear out, they stretch out.  You can get a chain stretch gauge at any bike store to see when you need a new chain (they also tend to last years).

I go through a chain a year and I don't ride much. But if you replace your chain often your cassette and chainrings will last years. 

I also ride more in my big ring - but I have a 12/27...

You should mock your cousin for only riding in the small ring.  Everyone knows that real cyclists only ride the big chain ring.

Cbire,

that is what go us on the discussion because I generally only use the big ring unless it is a ridiculous hill. I may be wrong for that but that is where I feel comfortable riding.

Yeah, they don't call it a granny gear for nothing

I didn't even realize there was a little ring on my bike until just now.

Nah, that's not an ultra noob question man.  Stick with big ring because it works nicely for you.

Your cousin is just too wimpy to use the big ring, hehehe!

"stretching out" is wearing out.

Chains don't actually stretch the way people think of it.  No part of the chain is actually getting longer.  The pins wear down from the chain constantly bending and straitening.  The holes in the plates wear from the same movement.  As the pins get smaller and the holes larger the chain gets longer from the added slop in the joints.  Because the chain gets longer people call it "Stretching"

Whoda thunk Trek was nice enough to put ANOTHER ring on there, just to prevent me wearing out the useful one?!

Thank You Thank You Thank You.

THIS IS THE ONLY CORRECT ANSWER. 

Front rings, cassettes and chains are wear parts.  They are meant to be replaced periodically.  Use them.  Replace them. 

Tell your cousin that he should not use the brakes on his car because they wear every time he stops.