My own psaht now: We can even see this “snowball” effect by just looking at the story of Purim. Just like Adam and Chava ate the fruit with the purest of intentions. Only to push aside the fact that Hashem told them not to. Likewise Mordechai told the Jews not to partake in the seuda of Achashveirosh. Nevertheless, the Yidden went, not to enjoy the gashmius, but because they thought it would be a chillul hashem. They too had justification for going, nevertheless, they were forbidden to go since they were told by gedolim not to.
This seemingly ‘innocent’ aveira was the main aveira which led to the potential destruction of Klal Yisroel.