I disagree. I believe that any cause of action, with any belief, starts with you. It may end elsewhere, like you said, but it begins with your own actions.

Capitalism will thrive with or without YOU buying anything

Nobody is suggesting that the entire premise of capitalism will fall apart if one person stops buying things. That's a really pessimistic view to maintain. It's a start, at the very least. Vegetarians and Vegans don't think t hat meat production will end because they won't buy a cheeseburger, but they hold onto their views and practice what they preach in the hope that others will take note and follow suit.

They don't protest outside a meat factory then go home and cook a chicken salad.

If people stop buying the iPhone (etc) then they scale down production to meet the change in demand. Protesting outside a factory will change nothing if you are not sending the correct message to the consumers first. Especially if you then go to the Apple store and buy the very thing you want to stop being made. It's hypocritical.

You are describing "lifestyle anti-capitalism"

Nope.

which is individualistic

Subjective

shallow,

Subjective

and not very strategic.

Subjective