Only one motherboard died for me, apart from that, my current machine was bought used, and I bought it some 5 years ago.
Once I had a problem with a noisy videocard fan (in my previous machine). I bought a new fan for maybe 2 euros and the problem was solved.
Power supplies newer died on me, the current one is 4 years old or so, though I change them more regularly than the other parts.
My computer cases always had all the sides removed, and they always had a quite powerfull and expensive power supplies, and I always paid big attention to routing the cables inside the case (I have always assembled the PC:s on my own except for my first 2 PC:s), so they don't touch or obscure anything.
I am always very cautious with static discharge when messing with the hardware, etc. I always read manuals carefully and do everything in the sequence written there.
Same is truth for my other stuff, like cell-phones, or Windows. The only reasons I had to buy new phones were because I lost one of them, and another one would have been more expensive to unlock (it didn't work abroad) than buying a new one.
So I don't think that the manufacturers greedily set everything so that the lifetime of the stuff is equal to the guarantee time, that's more of a conspiracy BS.
Or maybe my secret is that I only buy trusted and higher-end equipment, and newer buy cheap nomane stuff, and I always pay attention to use them right. For example properly recharging batteries.