When the Buddha tells people they should love people, what he says is, “even as a mother protects with her life, her child, her only child, so with a boundless heart should one cherish all living beings.” He characterizes lovingkindness as protecting. That’s what we're talking about with self-love: taking care of ourselves. So when you say “may I be happy, may I be peaceful,” you don't have to think “I don't know… I kind of screwed that up. I don't really deserve it.” It's going to something more fundamental. Mettā is bringing a sense of care and protection to yourself.