I always keep my PCs for about 8 years. Usually it is necessary to update the HDD/SSD and the GPU during that time, that is all. Mine will be 4 years old by the end of this year. I am now actively checking out 4TB SSDs in order to replace my current 1TB SSD.
This strategy may stop to work unfortunately. With the advent of ARM in desktop PCs, the PCs seem to become more monolithic. RAM and GPU not swappable, I think MACs don't even allow you to plop in more RAM. I don't like this development.
what? what PCs are you talking about that don't have swappable components? and how are those relevant? MACs is referring to something different than apple?