Re: Macs typically have a longer usable life than Windows PCs ...
On the other hand, Apple gave up supporting my 2007 iMac in 2014, even though it still works - only the Bootcamp Windows gets security updates these days.
My 2008 iMac has just gone out of support for new versions of the OS, which did irritate me as the lowest hardware they support for Mojave is less capable than my machine in both GPU and CPU. I can move up to High Sierra from Sierra and still get security fixes or I can do like I have with my 2007 Macbook and install Linux on it and be supported for quite some time. Linux Mint installed without issue and runs snappily on the old hardware.
Official support for Sierra ends September 2019 and, presumably, High Sierra will be around September 2020. That would mean 12 years of support for that hardware. Support for 12 years is pretty good and I am only irritated by the lack of further support because it seems to be artificially enforced given the aforementioned supported spec.
I have to confess that I have a newer machine that is a Hackintosh. That is an acquired taste but I did it because there was no path available where I could have an Apple machine with user upgradeable and replaceable components. I had a sketchy graphics card in the iMac which I only realised was a recall item after the recall ended. It promptly shat itself shortly thereafter. I would have preferred to be able to replace the component myself but didn't have a clean-room to remove the screen and dick about with the internal layout and custom card form factor. This machine will last a very long time and would only be hindered on the macOS front by a change in architecture from x86 to ARM.