In "Get Me Some Medicine," why does Fellis get so angry at David for saying that Meekew could beat Fellis in a fistfight?

Fellis is already feeling bad because he has been "beaten" by Meekew at college, because Fellis has had to drop out, while Meekew is successful. Then David--who always loses at cards--beats Fellis and takes almost all of his money. Finally, David adds to these insults by saying that Meekew, who is not a very big man, could easily beat Fellis in a fight. This is the last straw for Fellis.