A lot of the time the problem is people just can't let go of past mistakes. You make a mistake and the last thing you want to do is dwell on it and always have that regret. It will only make you bitter and ensure you continue to make avoidable mistakes. The best thing someone can do is to learn and start again with a positive outlook, but unfortunately there are a lot of people in this world without proper morals always trying to take advantage or wanting people to make the same bad choices they did.
The only advice we can trust is our gut and take everything we hear and read with a pound of salt.