Bigcharts.com shows Standard and Poors 500 index value increasing since spring of year 2003. Your only experience is during a time of generally increasing prices. If general market average values decrease you might discover how easy it is to lose money. You might study price histories. Consider how to respond to the worst possible trading condition - a long continuing losing streak. I find thinking through worst case scenarios to be helpful. Money management may refer to risk as a percent of equity. For example, suppose I risk 1 % of account equity on each trade. If I lose 20 times in a row, perhaps I lose about 20 % of my capital. I still risk 1 percent of capital, but my capital is 80 % of what it once was. I do not "blow out". Equity approaches zero asymptotically.