In my opinion, marketing is something that cannot be learnt, it is an inborn natural skill, which can only be sharpened. What can be learnt is product (or service) knowledge about the product (or service) one markets.
The best people I have met in marketing, have been school dropouts, who spent their time hustling on the streets when they were young and that experience made them to sharpen the natural inborn marketing skill that they already respectively had.
That is why not everyone who have spent their time hustling on the streets are good in marketing, unless they do have the natural inborn marketing.
And again not everyone good in marketing hustled on the streets, some hustled it out their different ways.