It did not seem to me that football is an activity appreciated from an intellectual standpoint. But, thanks to your posing the question, I found a good article in The Irish Times: 'The rise of the Football Intellectual', article by Ian Maleney, Wed. Nov 9, 2016. In it, Maleney references several authors on the subject.
But back to your question. First: Does, in fact, the entire (or nearly so in your estimation), populace of Vietnam enjoy football. "Asian U23 football championship is the "____________" for Vietnamese people." Increasingly, we are told "we all" - when "we all" most certainly do not - for example, have electronic devices.
As to "comic books" - it would depend on the style of comic book, yes? A comic book, like food, can primarily be a visual treat, if you will. Or, it can be to instruct, etc. Or, both. There have been literary comic books, for certain.
"Fodder" is used by the British for what you call "mental food." "Feast" doesn't apply.
How about referencing a literary work you reasonably believe to be known by your target population.
"Asian U23 football championship is the "____________" for Vietnamese people.
Or, make it personal. What is it about football that stimulates you intellectually, and what is your food/book that applies.