This is a Japanese saying regarding trading:
Buying is a skill, but selling is an art.
In English skill and art can be close/the same in meaning.
But in this Japanese saying art strongly outweighs skill.
However, I think that the saying should be reversed, with
buying being the art and selling being the skill.
The art aspect of trading would account for why so many find it so difficult.
'Art' as used in the Japanese saying or as I feel it should be used for buying?