I would not equate them with the KKK as they were based more on hate and I would say that BLM is based more on victim hood. I think where it has gone wrong is that they have been taken over by fanatics that have already come to a conclusion (that blacks are victims and the perpetrators are complicit bad people) facts be damned and anyone in the way can simply be run over. The grater problem IMHO is that such is tolerated from specific groups like BLM rather than treated as the asinine behavior that it is.
I'm really comparing the modern iterations of both organizations. In their modern iterations, both the KKK and BLM spread messages of hate and racism. If you were to say that BLM is based on victimhood, you would have to say the same of the KKK. The KKK believes that the minorities are trampling all over them. Likewise, BLM thinks that the whites are trampling all over them. They both show extremist attitude occasionally leading into physical confrontation. In fact, I'd actually go so far to say as the modern version of the KKK is actually less of a threat than the modern BLM. You see far more incidents of basic civil liberties being trampled by BLM members than you do from the KKK...and people watch the KKK like hawks so you know every toe they step out of line is reported.
I agree that it is absurd that many people find the behavior of BLM more palatable than other outright extremist groups like the KKK or the WBC...when, at times, the exhibit the exact same types of behaviors. I think that there are legitimate complaints about racism that can be raised, and do need to be addressed. Only an idiot would deny this. However, when you combat legitimate concerns through extremist methods, you will only build hostility towards your cause, not understanding and agreement. There is a reason why we respect the Martin Luther King Jr. or Nelson Mandela, or Ghandi figures...they are respectful men that served as great examples of how to actually change minds and get your message across. On the other hand, when you look at the xenophobic warlords in Africa or figures like Trump or organizations like the BLM, you see them as not changing anybody's mind and, in actuality, building hostility towards themselves and their causes.