Yes, of course. I know some people want to build something and then hand it off, but personally I love to actually use and improve the tools I make.

Even with my personal projects, I find myself going back to my old projects and adding stuff to them, much more often than I find myself starting brand new ones.

As long as someone also accounts for the cost to maintain a business relationship with the vendor. This has not been my experience.

Maintenance is easy if you don't suck at retention. As much as engineers like to build they also really enjoy gardening.

The only compelling argument I have heard for buy over build is "well, our engineers keep leaving". Yeah, because you are terrible at managing them - so no shit they leave.

A competently managed technical team has some natural attrition but the rates of turnover I see in a lot of companies that push this ethos is far beyond normal or healthy.

All software becomes "legacy" in short order if you are constantly hemorrhaging tribal knowledge and skills.