Unironically is monster (and energy drinks in general) bad for you?

I understand it's not healthy to drink soda in general. But compared to say Pepsi is there something in Monster that's extremely dangerous? My boomer parents keep telling me it will cause cancer/organ failure/rectal bleeding/etc.

Is monster super unhealthy or just another "yea it's not the best but one can a day won't kill you" drink?