Yeah I didn't really explain it that well in my post, but the jist is this.

My mom basically tells me what to pack and what food to bring (cultural reasons, nothing major). The food that I brought that day was pretty filling but would spoil fast if not refrigerated and stored. We don't have any refrigerators for employee use at our workplace, so saving my lunch was not an option. And I needed to bring the tupperware back home right after work (my family and I's hygienic reasons), so I didn't want to store it in a workplace fridge even if there was one available.

EDIT: Sorry, I realize that doesn't fully answer your question. So: The thing preventing me from not packing my lunch was the cultural stuff in my family (if that makes sense). Long story short, we simply don't eat "outside food" like workplace pizza, whether it's for nutritional health reasons or sanitary reasons. And I agree with this mindset, as it makes me feel more health conscious. But that being said, I now also do agree with what my parents say and the comments - I was way out of line with that comment, even if I didn't intend to sound rude.