Why might a boycott be a good way for people to protest a law or other action that they do not like?

It is a direct way in which the voice and sentiment of the people will be heard by government or the institution that they have a grievance with. It is when they refuse to buy or abstain from any service from a person or institution be it government or the private sector. For example, if government enacts an unfair law like suddenly imposing taxes that people can’t pay. They would refuse to pay it as well as not support any program or policy by that administration. When that happens, it would cripple that government both economically and politically until they would withdraw or make changes on that law that would be acceptable to the people.