Lego building as a hobby
My seven year old has that lego wind turbine at 0:14. He put it on an Amazon Christmas wish list when he was four, and I let him on the assumption that no-one was daft enough to spend that much on a 12+ lego set for a four year old.
So of course his grandad (my dad) got it for him. Had a lot of fun building it, it's on top of some shelves behind me now, next to the millenium falcon (not the 75192 crazy expensive one, the other one).