"bent" here means "A tendency, disposition, or inclination: "The natural bent of my mind was to science" (Thomas Paine)."

In other words,
those who are inclined to be pessimistic/negative/hostile or scornful would think you are a glutton for punishment

My understanding of "glutton for punishment" here is a person who acts like a fool for his pains,

So my translation would be: 爱抱怨（愤世嫉俗）的人会觉得你吃力不讨好。