Ego And Blindspot Barriers

From the book Ray Dalio's Principles:
In 1929 a 15 percent rally was followed by the greatest crash of all time. In October, to hedge against worst possibilities, I bought gold and T-bill futures as a spread against eurodollars. I was dead wrong, after a delay, the economy responded to Fed's efforts rebounding in a non inflationary way. My experience over this period was like a series of blows to the head with a basketball bat. Being so wrong was incredibly humbling and cost me just about everything. I saw that I had been an arrogant jerk who was totally confident in a totally incorrect view.

The point here is:
No matter how confident you are, even if you are right 9/10

IF you use LEVERAGE to go all in whether it's DCA or buying options, naked selling calls / puts,
that way you let that one time erase all your wealth because of your ego that you must always win.