The reason why many smart people fail to invest in real estate is that they become irrational when they see a property they desperately want in front of them. They end up borrowing as much money as possible from financial institutions in order to purchase the property that they desperately want.
Many of them tend to ""fall in love"" with the property too much and take it easy on various risks such as vacancy loss and large repair cost outlay, which should be understandable to them.