How do you use loans?

I notice that MP players never hesitate to pick up loans. I never was the MP player by myself and at the same time I have quite a lot of hours in the game and it gives me a good understanding how economic works in the game but I still have a strong habit to avoid any loans at any cost and I simply don't see the profitable usage of loans mechanic. Like, why I should take them if it gives me tons of inflation and raises my expenses via interest? (Another talk if we lead the decisive war for our existence, but any other cases?)