'hard' is best defined as 'requiring a skill a smaller percentage of the population possess
I disagree about the 'skill' bit. Skill can be acquired. There are many skills that few possess that many could acquire, if they wanted to. For examples, consult the Guinness book of world records.
I disagree about the 'skill' bit. Skill can be acquired. There are many skills that few possess that many could acquire, if they wanted to. For examples, consult the Guinness book of world records.