Given the amount of time people on hn spend using their computers, it isnt that surprising. Most people probably spend much less time commuting, but that amount of money is considered reasonable for vehicle maintenence expenses that probably recur more often than people buy a new computer
My last computer I put together about 5+ years ago (i7-4790k, 32gb ram) and did a mid-cycle upgrade a couple years ago (gtx-1080, 1tb nvme, large 4k display).
New computer is X570 mb, 64gb, rx5700xt, using an r5-3600 as a placeholder, I am still waiting on a 3950X, and only pulled the trigger early since my last system was acting up. I don't have the specific costs, but have spent around $1500 so far and will probably lose ~$50 on the 3600 when I upgrade and sell it off. Will probably be 4-5 years until I upgrade again, except I may drop a second and/or third nvme drive in or bump the ram to 128gb.
The difficulties I've had this time around have been around aesthetics, since I didn't have any experience with aRGB it tool a while to figure out what to get, and even then none of the aRGB supports Linux. The 5700 just got swapped in, and I've had trouble with that and will have to correct over the weekend, may wind up on Windows if it's too much of a pain.
I've mostly been working on my work-issued laptop, where I've had separate issues with the battery/charging etc the past month. In the end though, spending a couple grand on a computer every 3-5 years isn't so bad if you're actually doing work on it. I will say, I am surprised how much faster this system actually feels over my old one. Hopefully I can get it stabilized with the new video card soon.