Again, I think it is an individual decision. It depends on what you are willing to live with. Something that may be a make or break situation with you, might not be that big a deal to me and vice-versa. We are all individuals and have different tolerance levels.
People stay in relationships for different reasons, too. Some don't want to give up the nice house or the nice car, or don't want to have to get a job or not be able to go on the exotic vacations, etc. Some have really low self-esteem from years of living with addiction and they fear they will spend the rest of their lives alone. There are many different reasons why someone might be willing to stay in a toxic relationship.