I keep telling my friends who get really into stock investment, read some stuff, invent strategies - and end up much worse (sometimes losing money) than me just

I keep telling my friends who get really into stock investment, read some stuff, invent strategies - and end up much worse (sometimes losing money) than me just dumping everything into a few almost random indices: 1. Greed (not as a pejorative or a judgmental term, just this itchy feeling that you want more than you have even if you gain and are not satisfied) is the fastest way to lose money, whether through a poor investment or being scammed. 2. When you decide to play a game of stock investment, who are you playing it against? Being better than average (just market returns) means being better than the average (not median!) player, who in this case is some institutional investor. Do they really think that with a few online courses they can be consistently better than people who do this stuff for a living?