You vastly overestimate the resolve of most consumers.
It's probably closer to 95% of people who give up on their boycott once they realize just how enmeshed company is in their market and how much extra effort it takes to avoid giving them any money.
I haven't faltered in my boycott of nestle. It's easy to avoid all of their products (and their sub brands), as there are plenty of alternatives.
But you're right. Literally impossible to destroy them with boycotting alone, since the many many businesses who do business with them. My solo boycott is barely making a dent.
Major respect for having the resolve to keep boycotting that awful company. If only more people were like you, Nestlé would finally get some sort of punishment for their atrocities.
Not to diminish their successes in boycotting meat and animal products, but I would say they have a couple of advantages that someone boycotting Nestlé wouldn't:
Food ingredient labels.
Avoiding the entire industry rather than a subset of producers within an industry.
It's very easy when there's so many better chicken sandwich alternatives. Popeyes chicken for example, Wendy's. Not to mention the half a dozen local joints.