But what is competing with age of sigmar?
What other game lets me paint dwarfs with hammers and name them and read books about heroes and great battles.
What other hobby hands me elves and magic and tells me to paint my own magical effects?
Star wars x-wing competes with games, GW doesn't.
I play board games, of all types, I play video games (much less these days than when I was younger), I read books, watch movies, follow a few tv shows.
All of these forms of entertainment compete for my time, but none of them satisfy my urge to model and paint 50 satyrs and watch them charge into a line of swordsmen.
So yes, there are other games, x-wing is another game, but GW is trying to cut out competition, they're not a games company, they're a hobby company. They're warhammer. Age of Sigmar isn't marketed at gamers, because better games have existed and will always exist. For competition you can't get better than Magic, with a worldwide tournament network that's supported in almost every single country. Furthermore, changing your competitive angle in Magic is leagues easier than even x-wing, and transportation to farther competitions is dead simple. You put your deck of cards in your pocket and go.
If adults want a super technical competitive game there is chess, go, poker. There are amateur sporting events for competition, there are countless ways to compete.
There is only one way to dream up a fantasy army and play with toy elves.
Age of Sigmar is targeted at the person who sees a box of dwarves and thinks "boy I really want to paint that"
Then they look over at their friend who bought a box of elves and thinks "boy I want to see my guys fight his guys"
Warmachine and hordes has a tight game, and organized play. Almost nobody I know plays it. They love the imperium in 40k, the tales of space marines and the (sometimes) tragic brothers who fell to chaos. It's about the struggles of humanity in the face of an overwhelmingly hostile universe.
Age of sigmar is very similar to that, they've given you entire realms to carve out your made up empire, lead by your made up leader, be he a king, she a queen, an emperor, a pope, a priest, whatever you desire there is space for your story in this world. For the squads you paint to exist, to breathe and march against the forces of your friends who have their own story for existing.
Finally I would challenge your idea that Americans require competition. Why is it routinely written about by Mark Rosewater and other executives at Wizards of the Coast that the casual players make up the majority of magic the gathering card sales? The tourney players hound forums, finding optimal lists, rarely buying booster packs they instead prefer to buy from secondary markets to minimize the cost of buying randomized booster packs. Why is it in this hyper competitive game, with a huge international competitive scene, why are the casual players still more profitable? More desirable to the businessmen, the CEOs, the stockholders?
If, as you claim, america is so culturally competitive, why is the casual scene of magic the gathering still far larger and more profitable than the competitive circuit?