The social exchange theory postulates that altruism only exists when the benefits outweigh the costs to the self.
ðə sˈoʊʃəl ɛkstʃˈeɪndʒ θˈiəɹi pˈɔstʃʊlˌeɪts ðæt ˈɔːltɹuːˌɪzəm ˈoʊnli ɛɡzˈɪsts wɛn ðə bˈɛnɪfˌɪts aʊtwˈeɪ ðə kˈɔsts tə ðə sˈɛlf.