I’ll start with one: Never believe that financial management can make you rich.
Financial manager may not make someone to get rich but it will help the person in managing his money. It will not let the person to spend the way he wants if it is lavishly but to spend wisely. Not everyone will be very rich in life but there are people that are just average and living a good life and also secure their future with good financial management.
I think that is the basic core of financial management, it will help you manage your financials, it will guide you to make the right decision. So there is no trap in here except that you should execute everything to the T so that you will not get poor and on the contrary, multiply your money.
It could be as simply as the difference between "Need and Want", and that's where everyone should start. So I disagree about not believing on financial management. I think it is still a core on how someone could become rich because he or she will not the value of money and right spending.