Quoted from donkadelic:Hot Wheels makes what, 80 billion dollars a year? There are millions of adults who collect them, millions, not hundreds. Adults collect all kinds of dumb crap in case you haven't noticed. Transformers, TMNT dolls, MTG cards, you name it. Just because you think collecting toys as an adult is dumb (I would tend to agree), doesn't mean it isn't a huge industry.
Its not enough for it to simply be a 'thing' - you need the overlap between those that want said thing, and be willing to spend 6-10k on a pinball machine. You also have to look at how much they cross over their passion into other types of product.
I don't see a ton of hot wheels jackets/tees walking around town...