I've had roommates where we just ended up buying our own ketchup, mustard, soy sauce, fish sauce, Sriracha, and probably other things I can't remember because they were weirdos that refrigerated those things. I kept mine in the cupboard, they kept theirs in the fridge.
Almost all those things say "refrigerate after opening". Probably not a huge deal at restaurants as they go through them quickly, but it absolutely can and will go bad.
Depending on the PH levels they may never "go bad" as in, suffer bacterial or fungal growth. (Anything lower than about 4.6ph will have much lower chances of spoiling but this risk is not eliminated completely and there are plenty of people who get botulism poisoning from high acidity foods improperly stored, this is because while the bacteria may not thrive there, their highly toxic bi-products may persist even through cooking.)
But that's not the only reason we refrigerate stuff. Food, including condiments that are salty or pickled, are made of organic molecules, oftentimes many different kinds of complex molecules. These delicate structures begin breaking down the moment they're created the same way a jiggling lego tower will eventually become unrecognizable.
Refrigeration slows this jiggling and preserves the structure of these molecules, preserving the flavor and nutrition much longer than if you leave it out. If you go through those condiments fast, in less than a couple months, it should be fine, but everything eventually reaches a point where it doesn't have the same flavor or texture anymore and it won't be as nice as fresh ingredients.
If you keep those items in the frig, they will last for years. If not, you will have to replace them faster because they DO go bad eventually, even if it's just the taste degrading. Organic molecules are complicated and start breaking down the moment they are created, so everything food-related changes over time to "not food" or at least becomes flavorless and devoid of nutrition. Refrigeration slows the molecules from jiggling so much and preserves these fine structures.
It's just a choice. I don't really see the point of buying your own bottles of that shit unless it's just a matter of convenience. So come on, let's be honest, unless your roommate chain the ketchup the refrigerator, ya'll are just buying your own condiments anyway.
I mean, totally reasonable... just, unusual? I've never had issues with "cold ketchup" since it's kind of unusual to use more than a teaspoon on anything unless you REALLY love ketchup. Do you by chance have sensory issues? Like sensitivity to textures and temperatures?
No i get that, it's just that I can't imagine how goddamn cold that ketchup must be or how much you're using if it actually gets cold enough to be noticable and chill your fries. I've been on Earth eating fries for a long time, at home, at restaurants, at other people's houses, etc... I just don't think I've heard the complaint that the ketchup is too cold XD
It's fine, just like I said, different and kind of quirky.