I attended a business seminar where a facilitator a renowned professor, and Entrepreneur shared a story on how he missed out on investing in a small fintech start two years ago which as at today is worth $500 million. He said the team had approached him to make an a investment in the start but because he did not understand how the were going to make money since he didn't invest the $100k he wanted to write them. Today, he would have been $7.5million richer had he invested.
They say do not invest in what you do not understand which was largely the principle the speaker adhered to but what if despite not immediately understanding the business model and its profit making model yet your business instinct pushing you to invest. What should you do? Listen to the former or follow your instincts?
It is the dilemma of any person who entered the world of investments.
If someone have talented to investor, instinct, they sometimes won, but sometimes they are losers, that is simply it.
Throughout history there are cases, in the past, for example Coca-Cola, in the present the list is also long but Uber... those who believed and invested, won, without the need to understand them.
Then, OP, that "premise" that you mention "don't be uncertain about things you don't understand, blah, blah,..." is a theory from the investment school, but the real world is something else.
The issue here was not the 7.5 million profit, it was the $100k investment, he did not have $10k left over, since he would have earned $750,000.
It is cheap speech in the world of investments, always say: "... if you had invested..."