Red velvet's Bad boy and Psycho sound similar.

i was singing bad boy and was reminded of psycho. Yeah they both are different musically but the way both are sung is very similar. Starting with irene; then Seulgi; then Yeri; then Joy; then Wendy; then all of them together for chorus. And both these songs are hit especially with international kpop fans. Maybe people like familiarity from an artist rather than wanting different songs from them each time.