Upon reading your story a lot of thoughts got in my mind. I understand why you react in that way but I also understand why your friend came up in that decision instead of following your plan.

  People think in different ways, came up in different perception but have one goal and that is to become successful. We may take the same mistake like what other did but it doesn't mean we make it intentionally. Sometimes mistake can help us to realize that we're already misguided to the right path. But the most important is after doing the mistake we are able to lead the right path and we can also learn that we should listen to the people who have more experience than us.