In theory stronger intra-specific competition in comparison to inter-specific competition can lead to species coexistence. Also theoretically, strong intra-specific competition can lower the population density and thereby increase the extinction risk, especially under the presence of interspecific competition, and therefore can hinder the evolution of extreme selfish traits. Therefore the effect of intraspecific competition on the population-level performance is an important question in eco-evolutionary interaction. In social insects, intraspecific competition can take two forms, inter-colony and intra-colony ones. A bulk of sociobiological studies in social insects both empirically and theoretically showed general importance of the latter type. However, the effect of such intra-colony competition or social conflict on the group performance is still largely unknown. Here we review our resent studies on two ant species, Diacamma sp. and Pristomyrmex puctatus, in which we empirically showed how selfish social conflicts negatively affect their colony performance.