I'm not talking about boycotts in general, like say the Montgomery Bus Boycott, because we know those can work. I'm talking about "Company that sells product made me mad" boycotts.
Whether it's past ones like the infamous Call of Duty: Modern Warfare 2/Left 4 Dead 2 boycotts, or more recently like the brewing chud Pride Month boycotts (And if we're being brutally honest here on the flipside: The all-but-in-name boycott of that Harry Potter game a month or 2 ago), all of them seem to universally fail spectacularly and not impede their targets in any way.
Another example of a successful boycott to throw out there in the 1890 tobacco boycott in Persia/Iran. The shah was selling out the country to the British to support his family's extravagent lifestyle, to a ludicrous degree, and he made a deal with the British that would give them a full monopoly on the tobacco industry. The backlash was so severe and widespread, with religious leaders issuing a fatwa against the use of tobacco and even the shah's own concubines participating, that not only did the shah cancel the deal, but it also set an example for Iranian solidarity that contributed to the 1905 revolution, which was unfortunately crushed by foreign powers.
In the modern day, it's difficult to get people to agree on something and actually take action, and to avoid the conversation getting muddled. Lots of people are grillpilled, and the people who aren't grillpilled have brainworms. Americans generally have poor understandings of how actions like boycotts and protests are supposed to effect change, and it gets confused with an expression of personal identity rather than an actual tactic. It's herding cats.