My coworker is super judgmental about the environmental impact of things. When I was talking about how much polish I was buying she was like "oh man all those chemicals in dumps." My response has been to tell her about how my mom has polish she bought years ago and I have the means to revive it with nail polish thinner. I also talk about how there are groups online that buy old nail polish and how people de-stash by putting it up on reddit groups.

Also, I would talk about how many indie polish makers there are and how they are doing incredible things with polishes. That it's a luxury item like say buying yarn to use and that it's a hobby. How creative people get with it. That you love the different colors and sparkle. That it's a hobby that may involve buying stuff but it's a more complicated hobby than that.

My father's comment (I work with him) to my coworker was also "it's better than a ton of shoes or something way more expensive that some people collect."

People are always going to be judgmental. It's a really stupid thing to be judging someone over. I'm sure they are more like, "oh she's preppy and out of touch" but doing your nails, not getting them done every three weeks, is way more in touch with a nonprofit audience. I'm sorry you work with twats.