Three (anecdotal) things i've seen with Lego:
> Its a toy that old and young can play with together which is semi-intelligent/challenging. Parents and Grandparents seem to be the driver of sales for the physical product rather than the kids.
> They have brand deals with other popular IP which extends to Movies and video games, this is where you get your age 0-16 sales via brand recognition.
> The 30 year old man child demographic seem to bloody love this stuff. Think of it similar to lightsabers, Funco pops and novelty t-shirts.
There were some threads on HN if you are interested.
Kind of make sense because a lot people who played with LEGO in their childhood in the 80's / 90's are now at the age where they are more likely to have disposable income and get back into the hobby.