In the United States, more households own a dog than own a cat, but I believe there are more cats owned than dogs owned because people are more likely to own multiple cats than multiple dogs. Now I got a bunch of friends with multiple dogs and when we hang out the dogs are usually in tow. I got to say, six dogs in one house is chaotic. Six cats in one place just means the area smells of cat pee.
Same in Germany. Many more cats than dogs since most people who own a dog only have one, while having two or more cats is pretty common for cat owners. Now that I think about it: I really don't know anybody who has more than two dogs, while I know several people who have three or more cats. Also: many dog owners I know also have cats.
I had an Old English Sheep dog and 4 cats. That was fun. One cat very old, one an adult and 2 kittens. Always entertaining. And the oldest cat always knew when the Sunday roast was ready to take out of the oven! The old english sheepdog, liked to watch the soccer/football with me. He always got a chew when my team scored. In fact he expected a chew whenever any team scored. He knew when the ball was in the back of the net. He'd jump up, look at me, look at the TV, look at me, back to the TV then paw the floor.
I think it depends on the size of the flat or house they live in with the cats. If they are living on less than ~100 square meters: 3 cats are the limit. Above it gets crazy. On less than ~200 square meters: more than 5 makes them at least slightly crazy in my book. If they have a farm (or a similarly large patch of land) and all the cats are running around semi-wild: a lot more. I knew a farmer that had something between 15 and 25 cats living on his farm. Most of the time you could not see more than a handful at the same time. I think to be a crazy cat person you have to have them living in your house. On average I'd say above 5 cats is where crazyness begins. I know people who have 5 and they are sure they won't get another since that's where they think madness starts, even in a fairly big house.
I used to view that the standard for being a crazy cat person is qualitative, not quantitative. "If you treat your cats as children you are a crazy cat person whether you have one cat or ten." I have come to accept that anthromorphizing pets as children is normal though. Then I decided to create a quantitative rule. Children are exempt from this rule but I always figured a hard limit where you are objectively a crazy cat person is this: "If you own more cats than you've had decades of life, you are a crazy cat person." At least that's what I go by. Now a fifty year old person with five cats probably has more cats than she needs, but she is not a crazy cat lady. She just lives dangerously.