If your Facebook page is hacked, what is the usual way that happens?

My level of anxiety, worry and fear is through the roof after my fb account was hacked. It was the “Lily collins” hack and they ran ads through my business page. The page has been recovered but I have no idea how it happened. I’ve been reading everything I can find about how to stay safe online and reading about how things are hacked and trying to figure out what happened so it doesn’t happen again. I know I didn’t click any links or install anything in the days leading up to it but I can’t rule out malware on my computer (I’ve since taken it in to get wiped just in case). It’s possible they got into my email to get recovery codes and other info which I guess would be best case scenario.

So basically I’m just curious how most people, especially the business accounts they’re targeting, get hacked. Should I be concerned about hijacked cookies? Is it most likely a case of phishing? I’m so worried about “higher level” hacks that I can’t control, even though I’m not anyone important or rich they could target. Is this likely to happen again even with all info changed and all security turned on? I’m a complete basket case lately and can’t stop worrying. I just want to feel safe, or at least not completely vulnerable. Any insight is greatly appreciated!