We must train ourselves in good behavior towards what we call other people because one's self is included in the classification 'a people' and by developing a sympathetic outlook on humanity we will be changing how we treat ourselves.
One should see others as yourself and realize that if you develop cruelty it is going to affect you as well because it will color the choices you make.
One should see others as yourself and realize that if you develop compassion it is going to affect you as well because it will color the choices you make.
A person might think that there is distinction between cruelty that will affect others and that which will hurt oneself but that is mistake because the self can not be pinned down as a truth & reality and therefore the cruelty is completely unchecked in that sense.
Put yourself in the place of others and realize that they are doing exactly what you would have done given the same amount of delusion and if we punish them for it thinking 'a being is unworthy of kindness because of delusion' then we will also punish ourselves for being delusional using the same justification in mistreatment of ourselves.
Therefore if we want to succeed then we want a being to succeed and by being we mean any being whatsoever because we want to include ourselves and we are like others. There is no workaround this and otherwise one will have cognitive dissonance like 'we are all one as nature' and 'i am me and you are you, we are two', with this dissonance one will justify greed, self-sabotage, lack of discipline and all kinds of bad behaviors.
If we think our ultimate goal is xyz then it is the same for everyone else and we must strive to help ourselves to attain it also by helping others because in helping others we are helping ourselves by developing good qualities and thus strengthening the mind.
A person might treat others badly to indulge his excessive greed thinking 'another's loss is my gain' but his actions will put him in hell because he is playing a losing strategy.
It is as if a tree among trees could decide to produce fruit that kills other trees of the same kind, not realizing that it will destroy itself likewise.
Or like poisoning your own drinking water in order to hurt another and then keep drinking it yourself unwillingly because it's the only water left.
We only have one mind, it must be saturated to soak in good qualities which are pleasing to good people and only then will it invariably work for the benefit of all beings.
You are essentially training yourself & others all the time and to your best ability. Thus better you are as a trainer of others thus better you will train yourself and vice versa because your training ability depends on your faculties.
To sum up, you love others unconditionally exactly how you love yourself unconditionally but you don't have to love & tolerate bad behavior.
You should want the best for the best in you & others and be intent on the highest good.