The reasons are numerous, and each and every person is different. The common banner under which all the cases are carried is highlighted in the fact that humans are prone to mistakes, and sometimes they are not hit hard enough, or punished well enough to realise what the consequences are of their actions. We may temporarily realise that we were wrong in something, yet our arrogance does not allow that to last long, and we tend to brush that aside and continue in our usual steps.
Most of the troubles we get out of are blessings that have been bestowed upon us, and it is our job to keep those blessings clenched in our fists..One of the Holy Imams has said "Make a blesing last by being grateful". As discussed before gratitude is a great element of ones characteristic if they possess it.

