We tried that. We had a whole national protest movement, it lasted a year, millions of people were in the streets with the explicit goal of lowering police budgets.
Despite all of that effort, no police budget was defunded. Most police budgets have continued to increase. ICE funding has drastically increased.
So what's your plan to do something different? From where I'm sitting, the "let's kill cops" camp is more realistic than the "let's try the George Floyd protests again, maybe politicians will listen to us this time" camp.
This is an open problem for advocates of the Dark Enlightenment theory (Wikipedia) like Peter Thiel and Curtis Yarvin.
One of the most commonly discussed solutions is to surgically implant explosive devices into the bodies of your lead security force.