Yes there is a privilege aspect to leaving abusive situations - sometimes, it's a matter of finances keeping you from being able to leave. But abuse is much more complicated than that. Often, there's a strong emotional attachment, love for the person, even though they're abusive.

Abusers know how to belittle you, to make you feel worthless, and then to build you back in a way that you feel they're the only one who can love you.
And sometimes you love them despite their abuse.
And sometimes they also love you, while also being abusive.

There are a lot of reasons that a person in an abusive relationship wont leave. But we cant judge someone for not leaving, even if they are able to. The fault isnt the victim's, it is always the abuser's. If you want to blame anyone, you blame the abuser. There is no nuance here.