Two recent posts at Write That Down touch on the same issue. First, the author of that blog, Adam Bullied, argues that product management is intrinsically not that hard. The difficult part is learning to be a product manager:

I do in fact recall when I was first put into the role. It was exciting, but at the same time, really ridiculous. Not for any other reason than, I wasn’t working for a more senior product manager to kinda guide me a long and instruct me on what to do - I was in there on my own learning as I went. It turns out, this is ideal for me, but I recognize it’s certainly not everyone’s cup of tea.

This leads me to admission number 1: The job is damn near impossible when you first start. Actually, scratch that — it’s damn near impossible when you get 3-4 months in. This is because, at least from my experience, it takes people about that length of time to really wrap their heads around what it is they are supposed to be doing. And I believe this is where most would sink and maybe start believing, “this job is WAY too hard for me, or anyone, to really do.”