15-years ago or so a spreadsheet was floating around where you could enter server costs, compute power, etc and it would tell you when you would break-even by buying instead of going with AWS. I think it was leaked from Amazon because it was always three-years to break-even even as hardware changed over time.
One thing to keep in mind is that the curve for GPU depreciation (in the last 5 years at least) is a little steeper than 3 years. Current estimates is that the capital depreciation cost would plunge dramatically around the third year. For a top tier H100 depreciation kicks in around the 3rd year but they mentioned for the less capable ones like the A100 the depreciation is even worse.
https://www.silicondata.com/use-cases/h100-gpu-depreciation/
Now this is not factoring cost of labour. Labor at SF wages is dreadfully expensive, now if your data center is right across the border in Tijuana on the other hand..