Because to be a lawyer you need money to go to college and you have to work hard. Some people just don't want to do that, they like the easy money, the lifestyle, women, "respect" ecc. Even in the 50's and 60's, when the mob was at its pic, smart Italian-Americans were assimilated enough to become lawyers, but not everyone did. I think the mob is less powerful today because of the aggressive busts of the 80s and 90s by the FBI. Before the 70s, a mobster could do almost everything and getting light sentences. Now with all the rats, RICO, all them bugs, fingerprints, it is less attractive to be a mobster because there is a higher risk to stay in jail for a very long time.