sometimes they don't want to teach their friends for a reason that they would earn better or more
Incorrect, someone don't want to teach his friends because he worried if his friends will blame him after his friends invest in cryptocurrency. Or his friend will ask money because they know you're making a lot profit from the crypto you told to them before.
Actually teach friends to invest in crypto will make you earn more because the demand of the coin is increase (in case he buy it).
So true, this was my story, I was once like this until some people I used to carry along lose some money and they put the whole blame on my head, I felt so bad and I promised myself to never repeat such again, today I am very careful telling friends about a project that I want to invest money into, if I lose my money it's my money and I like it this way than other people losing their money because of me.