[ghaff]

I have replaced or added many of those things. People remodel, build new houses, etc. There are certainly business models around goods that people aren't renewing on an annual basis. Collectively it's probably fair to say that people in a country like the US buy a lot of doors even if it's a rare purchase for an individual.

[djbusby]

This place https://www.franklumber.com/ has been selling only doors for 50+ years.

One can model their business around market rules. It just might not be as huge as you want.

[ghaff]

I just ordered a butcher block counter from a local company. I've also ordered butcher block from a different company. At a rather larger scale there's Andersen Windows and Doors. None of these are or ever going to be--or presumably have ambitions to be--Home Depot.