PurposeThe purpose of this research is to investigate the negative impact of social media influencers (SMIs) (human vs virtual) on customer well-being. Additionally, it aims to explore how the fear of missing out (FOMO) mediates and regulatory focus moderates this relationship from the social comparison theory lens.Design/methodology/approachIn the first study, text mining and machine learning were employed to measure the level of followers' well-being in response to 40 SMIs (human vs virtual) posts on Instagram. In the second study, a randomized between-subjects experiment was conducted with three groups (human vs virtual vs control) and a sample size of 412 participants to confirm the results of the first study and investigate how FOMO mediates and regulatory focus moderates the relationship between SMI beauty product endorsement and consumer well-being.FindingsThe findings from text mining indicate that SMIs have a greater impact on consumers well-being, which is higher for virtual than human influencer. Additionally, the result of the experimental study shows the mediating role of FOMO in their relationship between SMIs and well-being. The moderator analysis reveals that there is a moderating effect of regulatory focus in the model.Practical implicationsThe findings inform marketing managers about the differences between virtual than human influencer in their impact on customer well-being in endorsing beauty product, especially among the younger generation.Originality/valueThis paper is among the first research studies that examine the dark side of SMIs, which diminishes their follower's well-being through social comparison theory lenses.