As mrerick points out, you can´t group the conspirators together like you seem to be suggesting. You need to draw a distinction between Brutus and the other conspirators in my mind. Note how Cassius manipulates Brutus into joining the cause - at times he says he does this just so that they can have Brutus on their side - a character who is respected for his honesty and honour - so they can gain favour with the Roman people. Cassius and the other conspirators thus seem to be focussed more on their own ambition and what they can gain from the assassination of Caesar. Brutus, at least overtly, seems to be far more focussed on acting for the good of Rome, though we might question if he is fully aware of his motives.
Do I think they do, or do YOU think they do? Personally, I don't think they did. Cassius is motivated by jealousy.