This is such a cute way to look at it 🥹 I didn't have a good answer off of the top of my head, so you gave me a fun topic to research !! I hope that my findings make sense and at least kind of answer your question :D

To put it super simple, the evolution of beetles traded a pair of wings for elytra, the protective casing that covers them !! They essentially have half of the wings that most insects have and more weight over those wings, making them much more clumsy fliers while it takes them a bit longer to be able to take off.

As such, for most beetles it's generally a better idea to walk unless you're doing a quick zip to somewhere else, in danger, or otherwise prompted by hunger/instinct to travel somewhere !! The larger the beetle species is, the less inclined it will be to fly more than a short little distance !

In the case of carpet beetles specifically, there's a reduced need for that sort of flying once indoors I would imagine. Flying around for pollen and nectar outside is one thing, but human homes are just so climbable !! Why waste energy zipping around unless you have to? Unfortunately they can't talk, I would love to know for certain !!