Does this graph mean what it is supposed to mean for the joke to work? The black line means I learn much quicker with less time investment, i.e. it is easier than all the others.
That is a common misunderstanding of how learning curves work. A steep learning curve means your skill increases more rapidly with the invested time. That means the subject is easier or more intuitive.
'If you change the axis then it makes sense' is not a great argument 🙂 but it does not matter, it is just a joke after all, so let's not argue. Have a nice day y'all!
It’s not changing the meaning of the axis though. The “required” part is implied. Could it have been made more clear? Sure. But reading learning curve into it is a little bit more of a stretch.
You nearly had it. The black line starts higher at "gaining skill" so it requires more skill to start learning but after short time you are gaining much more skill in the same time.