I would not underestimate the how shortsighted people are -- most of my peers are PhD students and most of them skip meals. Anecdotally, none of my flatmates eat breakfast, and my office mates often skip lunch and/or dinner because they have a meeting. The food offered at the university is a steal for the price and how convenient it is. These people are not out of money, they are (work) sprinting.
Is skipping meals bad? Like let’s assume the worst case: someone ate like shit all 3 meals a day. Instant ramen, spam, potato chips, ice cream, whatever. And then they skip a meal and on their next one they are 1.5 meals worth of food. Is that worse?
Yes. Skipping meals can condition your body to store away more of it because it isn't sure when the next meal will come, eventually making you fatter even if you eat very little.
cheap unprocessed brown rice, dried beans, frozen branded grocery store veg is not that expensive. (some spices help as well). Lots of poor students live on that.
Of course, it can't compete with super tasty fast-food places (laced with sugar/salt).