The game being successful wasn't luck but it being as successful as it was definately was. Block based games had existed for years before minecraft, I don't think there was any reason to believe that this one in particular was going to explode in 2010.

I don’t know much about Notch so I have no comment on them specifically, but “building the company and brand for years” can still count as “luck once”. Once you strike gold and make it big, you have a lot of leeway for mistakes, it becomes harder to fail. Case in point, Zuckerberg.