Here’s what they could do, start a “coffee club”, set up a stall right nearby Starbucks. Then campaign against them while providing caffeine at-cost (potentially even paying someone to sell this dirt-cheap alternative to Starbucks at all the same hours they’re open).

Sure it’s not the same (being from Australia, it boggles the mind how Americans even like Starbucks), but you’ll be offering an alternative to people who just want a caffeine fix and are open to being pursuaded into boycotting Starbucks.

Obviously, would only work if student association rules at the university allow you to set up food stalls.