Computers are tools, and if you need a better tool to do your job then get the better tool. Technology always marches forward and there will be better tools in the future. In general I get 5-7 years as a daily driver/work machine, then another 5-7 years as the basement file server/recording computer. I don’t need a supported OS or new software to do many things so an older machine is fine. After 10-15 years in service I usually sell on Craigslist for peanuts. The only Mac that I’ve had that completely die was my first Apple IIcx, which fried after a lightning strike some time around the late 1990s.