Ever since I lost a relatively considerable amount of money on my end during my college days, it actually taught me to be more careful and doubtful upon myself.

Sure, you could say that I became careful to the point that I always choose the safest path of all but it also eliminated the trait of being a risk-taker on my end. While it may not be as serious compared to other answers provided by others, it took a huge toll on my personality knowing that I became indecisive from being more assertive to my decision-making as a whole.

Like what I mentioned above, I did learn from my past mistakes and I am able to apply my "careful" personality to my overall welfare. Mistakes that I made were painful not only financially but also mentally on my part given that I used to be more of a risk-taker type of guy in the past.