The cost of a good office chair is comparable to a top tier gaming pc, if not higher.
That seems unreasonably short. My work computer is 10 years old (which is admittedly the other extreme, and far past the lifecycle policy, but it does what I need it to do and I just never really think about replacing it).
It depends what you're working on. My work laptop is 5 years old, and it takes ~4 minutes to do a clean compile of a codebase I work on regularly. The laptop I had before that (which would now be around 10 years old) would take ~40 minutes to compile to the same codebase. It would be completely untenable for me to do the job I do with that laptop (and indeed I only started working in the area I do once I got this one).