Can be applied to poker and trading. Not sure if professional gambler and speculator is the same. In any case both are skills to be developed.
See the lyrics at:
https://www.azlyrics.com/lyrics/kennyrogers/thegambler.html
Main theme of the song is:
You got to know when to hold 'em,
Know when to fold 'em,
Know when to walk away,
And know when to run.
You never count your money
When you're sittin' at the table.
There'll be time enough for…