Apart from forex trading, the most risky investment I've engaged myself in was a ponzi scheme called MMM. This is what put me into a serious depth that took me almost a year to pay back. I've come to realize that many a time when we fall for something of such is usually due to iur greed.For me it has to be Ponzi scheme, MMM to be precise. I could remember vividly it was 2016. The scheme promised 20% on all investment after a month. I invested money the first month I got paid my returns and capital. I became greedy and I invested it all. I lost everything.