What happened to him?

Who knows maybe he just stopped getting offered quality roles in mainstream movies.

He turned into a communist.

He went the Bruce Willis route and is taking tons of low budget films that require a very short shooting schedule so he can make more money with very little effort. Also he is very outspoken with his politics that are so liberal even Hollywood is taking a step back from them.

WTF Happened to JOHN CUSACK?

https://www.youtube.com/watch?v=J19pAaKlkVY

WTF Happened To This Celebrity? – The JoBlo series that examines the careers of stars and filmmakers who may have fallen out of the spotlight, and tells where they are now!

From early favorites like SAY ANYTHING to cult classics like GROSSE POINTE BLANK and BEING JOHN MALKOVICH, actor John Cusack certainly seemed like he could do it all -- whether in a romcom, drama, big-budget action flick or end-of-the-world epic, his everyman underdog appeal was always an asset. But over the past decade, the reliable star’s career has somehow veered into direct-to-video doldrums. Put some Peter Gabriel on the boombox as we check out “WTF Happened to John Cusack!”

The Guardian did a recent profile.
https://www.theguardian.com/film/2020/oct/04/john-cusack-i-have-not-been-hot-for-a-long-time

Seems to like to sleep late (in a very safe skyscraper), wear black, and express lots of outrage on Twitter.

Nice work if you can get it.

I actually liked Blood Money and Grand Piano.

El Pais had an interesting analysis on this recently: https://english.elpais.com/usa/2021-12-04/the-downfall-of-john-cusack-what-happened-to-the-best-loved-actor-of-the-early-21st-century.html

I get the sense that he is more occupied with social media than with acting these days.

Rumor has it that although he's a good actor, he's an asshole and a pain in the ass to work with. So now that he's older and isn't leading big moneymakers, nobody who wants to put up with his shit.

I don't think we're going to see a Travolta-style comeback from him.