They're definitely is a point of diminishing returns and a point where it can have negative outcomes but that's on the very extreme end. I also saw recently that there's a correlation between ultra marathons and colon cancer

It's common for people that do endurance sports to actually eat pretty low quality food in order to consume enough carbs. When I'm on bike trips I will pretty much eat just about anything including candy and things like maltodextrin in water just to keep myself going when I normally wouldn't eat these things. It's definitely not good for your gut. But overall is it better than being sedentary? Yes definitely