how can NCT DREAM ended up being the most succesful unit so far ?

People have been saying dream had the most potential for years. I personally prefer 127 though

as a non-fan, NCT 127 seems to be the most awarded unit. Oh well, facts are facts and NCT Dream has SM's best selling album of all-time.

It’s Dream’s first album, and Mark is back so the hype is there to start with.

As the others mention, Dream has been the most popular domestically. Resonance helped their fandom expansion internationally IMO, same goes with the other subunits

Dream are loved for:

1) they debuted very young and they clicked auntie feelings

2)they are friends that grow up together, and you can tell that watching them

3)the music is good, they were the first unit to win a show and a daesang

The real question is: why SM not milked them as 7dream as fixed unit from the start???