Why do people who buy multiple guns choose all the same brand?

I see a lot of people with 3, 4, 5, 6+ guns all from the same manufacturer. Glocks, be they 19x, 17, 34, etc. Sig Sauer, USPs, etc. I’ve never understood why someone would have multiple guns and not want to mix it up with different manufacturers. I understand why some people are loyal to certain brands, but surely a company like Glock doesn’t have 5-6 unique offerings that warrant ownership of them without getting bored and wanting to own something from a different manufacturer, no? I don’t really understand why someone would want to own 5 glocks or 5 Sigs or whatever other manufacturer when you could own a Glock or a Sig and a few other guns from other manufacturers. Does brand loyalty tend to play into this for most people? Is it purely an economic thing? I have never felt so confused.