Jewish people, historically were denied entry into many professions and guilds and were forced to be money lenders, hence the stereotype of Jews and money.
Many Jews, but not all Jews invest heavily in education. Hence, a wise person is an informed person and can learn to read and analyze stocks. There's no special magic to learning to make an investment. Read a book, dude!
Jewish people are stereotyped for no reason other than ignorance.
Jewish dude: I'm not cheap you idiot...you're selling this stuff for 10 x its normal price.
Ignorant fool: Damn, I wish I could figure that out.
Jewish dude: What a tool.