Not much work every few months turns into a lot over years, especially if you skip a few of those "every few months" events.

That is obviously true but doesn't mean as much as you seem to think. Washing laundry is also not much work but it adds up to a lot over the years, especially if you skip a few weeks of laundry every once in a while. That is not an excuse to not do it.

The answer is the same in both cases: acquire some discipline and treat maintenance with the respect it deserves.

I'm confused. It's too much work to upgrade dependencies, but not too much time to write from scratch and maintain, in perpetuity, original code?