I don't know if I can answer this question ... but you're missing a tad too much context.
1. What were the brands of laptops have previously owned? Especially the ones that died ... in relative short lives? Are you buying the cheapest laptops available, with the lowest tech specs, and are in no way possibly upgradeable because they're factory sealed from the start?
2. Are all of your computers dying on or before the year and a half mark?
You mention superfetching as a problem. Are you sufficiently buying laptops with more than sufficient specs and not overwhelming cheaper models with apps and programs that the laptop was never meant to run in the first place? Or if they could run them... can only run them at suboptimized/underwhelming results?
Do you run diagnostic and optimizing programs to clean up your system ... possibly burdened by adware, spyware, and useless programs that may run in the background that you willingly uploaded but don't need or use anymore?