Then it sounds like you know everything you need to know about them for how your life operates.
For your world experience they are not big, as that is pretty much the definition of big as it relates to personal context. Based on what you have written i suspect you wouldn't recognize their songs.
I first encountered them in alternative music contexts, but they get played in more mainstream rock and pop contexts too.
They sound like pretty much every other band who goes mainstream, sells out (something they understand having sold their souls to Mormon), featured as soundtrack to films and fancy themselves as 'change makers' and 'revolutionaries' aka The Killers but are the same corporate ass lickers as the rest of 'em.
The fact that The Church and LGBTQIA+ is now the hobby horse of Dan Reynolds and his 'Believer' film is absurd. Reynolds bites the hand and wants the church to change to HIS STANDARDS whilst enjoying $$$ from opposing the church. Blaming the church on his wife's mental health troubles is less than noble. But typical, as Mormons enjoy blaming Satan, anti's and the like.
Never heard of them until 18 mo ago when my I asked my grandkid, never-ever-mo, 9 yrs old, lives in mid-west, what his favorite band was. I'm a fan now--any successful human being who challenges stupid Mormon garbage is great as far as I'm concerned. Is the church going to kick him out?
I don't know who they are either. I only listen to 50,60,70 and only some 80's music. I don't watch contemporary movies either. I do notice some terrible music that plays in some commercials. So maybe I have heard they music in a commercial. I didn't like it. I guess I'm just spoiled with the oldies, I can't bring myself to lower my standards as I feel. Contempaorary music just makes me feel like a nobody without any taste. I'm 43.
Nobody here watched the NHL Stanley Cup finals? They rocked T-Mobile arena before the final game. Nobody watched halftime of the NCAA championship game tonight? Halftime show....Imagine Dragons. Also some national Vegas ad spots... https://m.youtube.com/watch?v=tLzoumT3BJc