Or we figure if a little feels good a lot would feel great.. and off we go into addiction. I like the framing of sin as the abuse of our God given instincts. Gluttony, lust..
I remember the first time I heard, in RCIA I believe, the phrase "the glamour of sin." Yep, I thought, that nails it alright..
The test is to learn the lesson with the minimum amount of damage to ourselves and others. I flunked that one.
There is nothing wrong with our instincts. How we apply them can be; the intent is what counts.