I used to edit a newsstand leisure magazine here in the UK. It was founded in the 1970s. We sold about 18,000 copies a month in our peak, making us the market leader.
I'm not the editor any more (I went off to do something else) but the magazine is still going. It won't surprise you to learn that it sells much less than it used to.
But that's not because the magazine has got worse. It hasn't. The writing is still as good as ever, the news reporting still pretty sharp. It's not because the market has changed. It's not because you can get the same information online for free. Much to my amazement, in 20+ years, no one has really catered for this particular market online - there's a lot of chuntering on forums and Facebook groups, but no one really doing compelling content. We were turning over £1m+ a year. I don't think anyone is even turning over £50k writing about this subject online.
So what changed? I think it's ultimately about attention. When I edited the magazine (c. 2010), people still chose to spend part of their leisure time reading about one of their hobbies. We were a fun way to do that. Today, people don't need to spend £5 to happily while away a few hours: they can just scroll through their phones. The magazine habit has gone.
Crucially, it's not that the information has gone online. It really hasn't. I read all the various forums and groups, and still when the magazine plops onto my doormat every month, I read it and find a load of stuff I didn't know. It's just that the time that was once filled with reading magazines is now filled with something else.