The theme was more or less was the haves verses the have nots, we all know this. It's pretty much thrown in your face when it states that the rich left Earth so that they could continue their way of life. Kinda like how the rich are screwing over everyone else so that they can continue their current way of life. So once you establish that that's the theme of the story, the rest of the themes are easy as hell to spot. The movie is like a representation of what the director thinks could happen if the massive greed of the world isn't checked in another 100 or so years. I could honestly go on and on about it because to me it was just shallow as shit what the director was trying to portray and they all related to current world issues that are going on or have recently happened. I'll skip that though because I'm sure no one really cares.
It also doesn't help that I'm a Sci-Fi fan and I also thought Section 9 was fantastic compared to this. It may also be because I'm not well-versed in South African issues so I simply missed his messages (aside from apartheid) due to plain ignorance. However, in that movie, I felt bad for the main character because he was just trying to go back to his normal life and once he realized he couldn't, tried to do what he felt was right before he thought he'd lose everything which felt suspenseful.
In Elysium, I wanted to care but I kinda didn't because Max didn't feel relateable to me. The events that happened to him were definitely unfortunate and fucked up but you already knew he wasn't gonna die before he completed his life's objective especially when it was discovered that he'd die once the information passed on from him. After that point, none of the in-between shit matted to me. I never wanted to roll my eyes harder. What I DO find pretty badass though is how he was pretty much handicapped the entire time he had the exo-skeleton on and still managed to wreck shit the whole time.
I know you're not really supposed to expect much from an action movie but I felt like this was supposed to be an action movie with a moral agenda and I took it even less seriously than a person normally would. I wasn't engaged enough to turn my brain off so my brain instead picked it apart.