Won't it also kill you if you put something acidic in the bottle? Like water with a spritz of lemon? That's why copper pots have a lining, anyway. https://en.m.wikipedia.org/wiki/Verdigris

Yup, and although correct about coppers antimicrobial effect it only kills bacteria on contact. So I suspect a majority of any bacterial contamination in the water, will never come in close enough contact with the copper walls for it to have any real effect.

Water bottles, if not cleaned properly with a soap and brush on the inside, will be coated with a bacterial "lawn". Copper prevents that. Lots of bacteria need such a lawn to propagate, only some can multiply without a substrate. So even if the "free" water part won't be desinfected, copper has an overall positive effect on the bacterial content of your drinking water.

As someone who washes my (steel) water bottle at most 1x a week, and drinks ~10-14L of water a week, I've never gotten sick from drinking out of my bottle before.

You can usually tell if the water in your bottle is going bad / filled w bacteria..

Same, except I wash it like once in a blue moon lol.

I have to at least rub the area where I drink otherwise it will smell within less 2 days

I don't usually touch the bottle with my mouth, so I guess that allows for a bit more leeway.

Do you hesitate to drink water from a normal glass or cup as well?

No. I was just explaining why copper is better in that regard, not that I would personally care that much. I do prefer stainless steel, because it is more robust, dishwasher-safe and cheaper.

normal glass goes into dishwasher after every use. Those water bottles are more of a hassle to clean properly

That actually makes a lot of sense, I did not know that. Thank you!

Everybody uses glass for water even if it does not kill bacteria. Shouldn't be the main factor to choose one over other. People must filter their drinking water and remove the pathogens before filling their drinking bottle in any case.

If this is not possible, take in mind that your immune system can take care about bacteria. In 99% of the cases after a learning period, local bacteria will stop being a problem. Unless your live in areas with very unsafe water sources or particularly dangerous organisms this shouldn't be a main factor in the choice.