Ronaldo is absolutely bigger than City, so too is Haaland which is kinda my point. You put Haaland in a United kit and he probably sells 1m shirts alone.
The idea they're buying them is no more crazy than the idea United buy them. City are already here thats the point. It may have been necessary in the past but unlikely given out shit sale growth looks far more organic than our others sources of income. With a nice bump since Erling which makes sense. Its easily dismissible for the now.
If the numbers years ago matched other income streams it would be than too but it doesn't. Why would City start buying them up now when we weren't even that big a seller 5 years ago? City didn't even register on lists (globally) like these till around 18/19 season onwards, we'd sometime be 4th but nowhere near the Chelsea number and have then crept up, a couple of years after Pep and when KDB became our first real superstar.
Not to mention the idea we're in the top 4 in the first place is disputable on a lot of levels as there's various figure putting us anywhere from 6th behind the big 3, Untied, Liverpool, Chelsea plus Arsenal and Spurs to us being 4th. There's literally nothing remotely out of the ordinary with our shirt sales figures for people to make said accusations (one of the few places funny enough that can be said). They don't need to buy shirts for legitimacy, buying trophies and big name players is enough to get youth on board.
I'd also say by most metrics our shirt sales are on a par with PSG a club who are in very similar circumstances globally and followed a very similar trajectory lagging behind a bit cause of their superstars.
Here for example is 2016
https://www.statista.com/statistics/945048/football-jerseys-sales-by-european-club/ and we're not even on the list so half a million at most.
By 2021 (5 years with the current Pep team)
https://www.statista.com/statistics/1118294/football-shirt-sales-by-club/