“Through thick and thin” – which is the bad one?

Is thick the hard times? or thin?

Shut up. don’t try and answer like you know. no one knows. it’s just a thing people say cuz people used to say it. But for realzes: are thin time good times cuz there’s not a lot of width to get through like in the thick times? or are thick times the good times cuz there’s more luxury as opposed to the time where your waist & wallet are thin?