I eat 'junk food' often (understand, Fast-food during daytime, and often cookies instead of a regular meal for dinner). And that's basically because I'm a busy student, with few free time, and I must admit I don't really want to spend even 30 minutes of cooking every evening. Paradoxally, when I decide to do a good meal, I can cook for ranges from 2 hours to 2 days.

So I guess it's probably out of lazyness when I turn to junk food. Plus a good proportion of it tastes quite good.