In a certain sense this is true. Giving to charity is a self-interested machination because the giver gets something out of the transaction: satisfaction, a belief in their own goodness and self-worth, the esteem of others, maybe a ticket to heaven. But in a more useful sense this is false. We use "self-interested machinations" to describe things that are deceptive and harmful to others, not adopting puppies. Even people who apply the nihilistic self-interest-all-the-way down argument to neutralize criticism in one case will tend to abandon it in another and become the critic.