Try this thought experiment: spend an afternoon convincing yourself that nothing matters. That we're temporary arrangements of atoms, cosmically insignificant, that your preferences are just chemistry. Now check—do you still prefer warmth to cold? Company to loneliness? Understanding to confusion? Of course you do. You cannot talk yourself out of caring, even when you know caring has no cosmic permission slip.
Which reveals something quite strange about ethics. We assume we care about others because they matter. But turn it around: we care about others because of what indifference does to us. When you ignore suffering you could prevent, something inside you begins to corrode. Not guilt—something deeper. The part of you that can distinguish between things that matter and things that don't starts fragmenting. You become the kind of person who can't tell the difference anymore.
This is why we protect forests, extend rights, care about animal rights. Not because the universe validates these choices, but because the version of ourselves that could casually destroy whilst knowing better becomes unbearable to inhabit. Cruelty doesn't just harm the victim