About the difficulty level, I’d like to add my experience.
I leveled all the chars to 30 and currently I completed pyro and ib (and working on the zealot) legend. My very big step in legend happened applying Avar guides and changing the pc hardware (from barely fit [old 950gtx 2gb and super old i5 2400] to a little better fit [1060gtx 6gb and i7 3770]) (almost 3 years waiting for intel & nvidia serious next gen and still waiting )
Just these fixes changed completely the experience, now (if the ping is forgiving) I can even carry the group.
My point is that this game is complex.
For being enough safe, you need to know the maps, the builds and how they work together, the mobs and how they behave, have a good hardware (the one proposed as min requirement is not enough, after the hw changes I made, I can choose, during a wave, which single entity I’m going to hit, before it was more “lets swing and hope”), having good teammates who think logically (the more, the best), that thing called ‘position awareness’, the ability to quickly understand the priority/importance balance required in the different situations.
And on top of this, the quirks… you need knowledge also about all the bugs, sorry, the intended features , related to maps, mechanics, characters etc
So, sometimes it’s almost like working