idiom requests - Word or phrase for "it won't change anything, but we'll protest anyways"

In elections, you may "cast a protest vote" for a candidate who you know won't win, but whose vote total you want to increase. This helps show support for the candidate's message or ideas. Or, it helps show public dissatisfaction with the other candidate, even if that candidate wins the election anyway.

In other contexts, you may do or say something
"just to make a point" or "just to make a statement."