Regarding hardware : i manage that by looking at the prices of new laptops and observing that i can buy ten times the used one i currently have for the amount of money. Moreover, since CPUs model numbers stopped being of any use to intuitively place them on a scale of performance, i decided to not obsess with that like i used to from the 386 to the P4.
My biggest concern is (was) with software updates ! On linux systems configured for general desktop purpose, i find it is easy to endure some regressions (esp. regarding low latency audio, and if wine is involved) a few times a year. I always start with a minimal system but years passing, with the need to try this or that app, i end up with mountains of packages installed;
i used to like to start fresh every now and then, but nowadays i feel it would be just another manifestation of procrastination so i just use the thing.
My current setup being based around software that compiles on many platforms/architectures, i'm not really concerned by a potential hardware failure and change anymore.