You're thinking about it wrong, because the very moment that Broly breaks his force fields is the moment he'll realize that Broly is stronger than him. And that's going to be something that will surprise him due to being something that people stronger than him needed to work for it to break. I was showing these cases, yes, but I agree that Broly would be able to break those things (be immediately or eventually), and when those things break (be with one or multiple attacks), Thanos would realize that Broly is not to **** around and just hax him. Dude's arrogant, yeah, but he's not stupid, especially when he made those force fields to tank attacks that he himself couldn't.