Consumer boycotts are usually explained as withdrawing revenue from a company. The revenue effect is generally small, and the pressure that produces change comes from elsewhere.
The direct revenue effect is usually modest
Participation in a boycott requires sustained behaviour change from many people, and sustained participation is difficult to maintain beyond an initial period.
Most consumers are unaware of any given campaign, and switching costs, habit and convenience keep purchasing patterns stable.
Measured effects on sales tend to be small and temporary, which would suggest boycotts fail if revenue were the only channel involved.
Reputation is the actual mechanism
A boycott generates coverage that attaches a contested issue to a brand name, and that association appears in search results, staff conversations and investor questions.
Firms invest heavily in brand positioning, so a persistent association with a controversy threatens an asset worth considerably more than the disputed sales.
The response is often a policy change presented as unrelated to the campaign, which allows the firm to resolve the reputational problem without conceding the principle.
Target selection determines feasibility
Campaigns succeed more often against consumer-facing brands with visible names than against suppliers whose products reach the public inside someone else's packaging.
Where the target holds a monopoly or supplies an essential service, consumers cannot withdraw, and the mechanism has nothing to work with.
Some campaigns therefore target an intermediary, such as a retailer or advertiser, that can be reached and that has leverage over the actual subject.
Clear conditions make resolution possible
A campaign stating precisely what would end it gives the target a route out and gives participants a way to recognise success.
Without stated conditions, a boycott can continue after the underlying issue is addressed, which erodes credibility for later campaigns.
Announcing the end matters as much as the demand, since a campaign that simply fades leaves no demonstrated result to point to.
Costs and legal limits vary
Boycotts impose costs on workers, suppliers and franchisees who had no part in the decision, and campaigns differ in how far they address that.
Certain boycotts are restricted by law in some jurisdictions, particularly those directed at foreign states or organised by businesses rather than individuals.
Because those restrictions differ by country and by state, and because they are amended periodically, organisers generally take local legal advice before beginning.