You're right, we are just a collection of atoms, molecules, subatomic particles, energy transmissions, electrical impulses. Ultimately it doesn't matter what we do, because at a very basic level all of our actions are nothing more than the creation of heat. Conversion of matter to energy. Nothing that you do ultimately matters. Go kill your best friend, go masturbate in the street, go wreck your car, it doesn't matter. It's no different fundamentally than any other human activity, and in the grand scheme of things it means nothing. Doesn't that sound liberating? Whatever you want to do, go for it!