Lower Lifespan Components?
Electrolytic capacitors are probably the most common short life component.  Some are only rated for 2000 hours or less, which really isn't much for many devices.  However, their life can be significantly extended by running them below max voltage and temperature.

LEDs are another component that wears out with time.  Again running below max rated current will extend life.  For good LED life getting it from one of the few major manufacturers, and making sure there's no cheating in the supply chain, is important.

Photovoltaic cells also degrade with age and use.

The cathode coating of vaccuum tubes wears out.  As a result, the work function goes up and more anode voltage is required to get the same current.

The fillament of a incadescent bulb keeps shedding atoms, and eventually wears thin and breaks.  Fillament life is inversely proportional to something like the 12th power of the applied voltage (it may not be exactly 12, but it is quite surprisingly high if you haven't thought about it before).

Metal oxide varistors (MOVs) wear out a little every time they absorb energy.

Then of course there are batteries, fuses, and the like which are intended for limited operation, but that's not what were talking about here.

Most other components don't really wear out with use as long as their specs are not violated.  Plastic will eventually degrade, silicon dopants will diffuse, etc, but these are such slow processes to be irrelvant in normal settings.