Gang members is not really gang soldiers though, right? With a number that big, I think they must be counting a lot of people who wear a gang's merch/colors/etc, but aren't active combatants. At least I hope so.
They inevitably crop up everywhere where police represent more of a threat than protection. Kind of like the free market springing up to meet demand, in a kind of sick and twisted way.
Gangmembers are older(and less dangerous by themselves) and some have gone through 'banging', others have joined through other means. They used to have the kids do the banging since laws are more lax on minors, and the kids are usually the hot heads who need to prove themselves. Members count the money and are in charge of administration, when organized proper. Im sure there is more to the heirarchy but usually a member wont come at you by themselves. they send the foot soldiers if they have beef with someone. Members are fairly weak, drugged up, care about the money. They come at you with numbers. Bangers are extremely dangerous by themselves.