They are fighting those things by fighting the system that causes them.
I suspect you think hundreds of years of oppression of poc makes no difference to the current generation, that they are not living with the consequences of the way generations before them were treated.
I suspect you haven't considered that black families don't have inherited wealth in the same way many white families do.
I suspect you haven't considered that the current generation of black kids live in a society that demonstrates it values their lives less than white kids by both stopping and searching them and killing them more often.
These kids are killed by the people tasked with protecting them, they often grow up without fathers to offer stability and guidance because the government is profiting from their incarceration.
'African Americans are more likely than white Americans to be arrested; once arrested, they are more likely to be convicted; and once convicted, and they are more likely to experience lengthy prison sentences. African-American adults are 5.9 times as likely to be incarcerated than whites and
Hispanics are 3.1 times as likely.4) As of 2001, one of every three black boys born in that year could expect to go to prison in his lifetime, as could one of every six Latinos—compared to one of every seventeen white boys.5) Racial and ethnic disparities among women are less substantial than among men but remain prevalent.'-sentencingproject.org
Thanks to historic racism they often grow up in low socioeconomic areas, lacking resources and opportunities.
Often, gangs are the only thing offering these kids a feeling of value, protection and opportunity to improve their lives in a society that demonizes them.
You fight that by creating resources, offering opportunities, improving funding to organizations offering support.
The argument to defund the police is to allow funds to be diverted from the people disproportionately stopping, searching and killing these kids and channel it to organizations creating resources and offering opportunities and support.
If you are against defunding the police to allow other services to provide support that they have training in but the police do not, what's your answer for solving the problem?
Or did you just want to blame people for not solving a problem you have no solution to?
Also, who said they are not fighting gangs and drug dealers other than you?