

It requires more space than a “native” installation, but that’s about it. Its impact on memory and CPU are very minimal, nowhere near VM levels because it’s not full-on virtualization. Docker containers share the host’s resources rather than creating virtual everything for themselves. Think multiple Linux environments sharing one kernel and drivers and libraries and whatnot. Except the runtime has strict control over which container can use what and how.
So Docker costs more in space. And space is cheap. It’s a price well worth the features it provides and enables (networking, orchestration, etc).
That’s the reason I don’t bulk upload books to my Kindle. Because I know I’ll be spending way too much time thinking about what to read next. Instead I only acquire books when I’m done reading one or close to it. And I only get more than one when they’re in a series.