There has already been one good, detailed answer given. I'll take a different approach and offer you a different angle to view the decision from.
Personally, I don't like the phrase "overclocking"- it paints a picture of pushing something past it's limits and, with your concerns being a good example, tends to imply risk as a part of it's very nature. I would say a more accurate and constructive description would be simply "tuning" or "clock adjusting". The system BIOS is going to instruct the processor, memory, or chipset what speed to run at regardless of whether you leave it set to automatically do so, or whether you specify the exact settings yourself. All components are mass produced, and the default speeds are set low enough to ensure that every unit can produce that level of performance, even with the variance in unit quality that's inevitable with the production process. So, realistically, the factory clock speed is going to be far short of the safe potential for about 90% of the individual units sold. This also means that in most cases, the default voltages running the default clocks are actually higher than your particular processor actually would require. So, if you remove the idea of default clocks being the baseline, you technically are already increasing the rate of wear and tear on the processor compared to how it could be manually tuned for the same performance.
In reality, you are going to almost always upgrade before burning out any component as long as you keep within a reasonable voltage range. So, if you want to be safe, the most sensible choice isn't to not adjust the factory clocks, bur rather to find what is considered the top of the "risk-free" voltage range for your processor, then work on finding the fastest stable clock speed that would be possible using that voltage limit.
There are definitely those of us who "over"clock and know we are running our systems into the ground while doing so, but rational, sensible adjustments to a system are nothing to fret about making. It's only those who haphazardly start tinkering that end up generating the stories and perception that there is some degree of risk that is unavoidable.