Originally Posted by DMF
But as a general rule, heavier components last longer — more material in them.
I don't think that's a good general rule anymore. Better materials can be both stronger and weigh less.
A department store bike frame, for example, is made from low carbon content steel so they have to use a lot of it to make it strong enough. A high tech steel bike frame, on the other hand, can have much thinner tubing wall thicknesses to make it much lighter in weight and still be stronger.