I think I read on some Wikipedia page that Pokémon makes a majority of their money off merchandise. I think they can wait 7 years for a new game because someone born last year, may not get a Pokémon game until their 9 and they would miss out on 7 years of merchandising and potentially not capture the audience at all.
I know 9 is pretty young already so let’s say it’s a 7 year old and now they are 14 or whatever.