I don't think it's easy at all. Try to come up with an original plot for a hollywood big budget time travel movie. Take the plot of Edge of Tomorrow. I could never come up with that. Ideas are easy when it's just "Grand theft auto in space", but actual originality? Extremely difficult.
On the other hand I ditch a handful of film/TV ideas each week.
Many because they'd be crap of course, but the rest because there's no way in this lifetime I'll have the resources to bother thinking about them, never mind have the time to actually write them out.
Gotta do regular people work till I die. So glad I was dragged out of the universal energy just to pay rent for 60 years haha. Fuck I wish I could afford to do something arty farty instead. Such is life.
I passed my GCSE English literature (end of high school exam in UK) writing a time travel story, haha.
That expression, "ideas are easy, implementations are hard", is lacking nuance. No, new ideas are ridiculously hard: can you have the idea for an alphabet if you have never seen one before?, even the banal equals sign is a ridiculously hard idea, Euclid and al-Khwarizmi never had such an idea [1]. Ideas are hard, implementations are sometimes hard, idea collages or idea twistings are almost always easy, given a ripening context: sliced bread; sell things, but on the internet.