Board Thread:Spoiler Discussion board/@comment-37211085-20181023122331/@comment-75.179.172.17-20200727011219

Her sin is Gluttony because she just wants more. More power, more knowledge, more anything. She tricked both and took their boons, she studied and studied, she wanted Meliodas to love her. She just wanted everything.

'Gluttony means over-indulgence and over-consumption of food, drink, or wealth items, particularly as status symbols.' It's not just food related. There's the saying 'glutton for punishment'.