Sadly, "belief and hope" hasn't worked for entire swaths of the population. If "belief and hope" worked, we could just "hope" there wont be riots and everything would be merry.
In reality, every two months something horrible happens happens and gets on the news. It probably happens much more than that and isn't on the news. And if it wasn't on video -- it is like it didn't happen.
It is rare to have video. It is even more rare for a charge. Even more for a conviction. I dont think looting is the answer here, but i seriously question the judgement of people who actually think there is no problem of police violence.
Even if you think that police violence is rare, there is the added problem of no consequence. I grew up with case after case, the most memoriable wones were https://en.wikipedia.org/wiki/Shooting_of_Amadou_Diallo and https://en.wikipedia.org/wiki/Rodney_King#Beating
Any time a person is killed or treated wrongly is terrible and police should be held accountable. But I believe it is more to do with rotten people than it is a rotten system.