minority gangs will never be getting legit businesses because they are structured in a way that gives no support for older, veteran members.

Whereas a wiseguy who is 60 and has been a gangster 40 years can have the money and influence to venture into legit stuff, the 17 year old gangbanger can't. And by the time those guy get older they are all either dead, serving life in prison, or leave the gang life.
Gangs centered purely around drug dealing aren't good for keeping older members. They should branch out their activities and set up a vertical leadership structure like LCN.