Guitar teachers often get stuck on this question because there is no simple answer. Beginner guitar students likely have their mind set on some kind of general goal. For me it was being able to play Led Zeppelin, AC/DC, Pink Floyd, The Eagles, Queen, Kiss and others. When I began I had no idea what was involved. I just imagined guitar was like a puzzle that you just had to solve and once solved was easy. I was partially right but what I did not realize was how much fine motor skill development was involved with learning guitar to the level for which I aspired. I think if I had been told that guitar would take thousands of hours of repetitive exercises I might have thought twice. It was like I was expecting to climb to the top of a small hill but instead found myself ascending Mt Everest. Now I don't want to scare you off from learning guitar because it's not all about reaching the summit. Every level offers a better view than the previous one so it's really about how high you want to go. How hard depends on how high.