To begin with, idealism is the concept of acting according to what you perceive as
perfection. Brutus avoided reality by creating a world that he seen fit. During the murder of Ceaser he justified it by calling it a sacrifice, rather than the blood bath it actually was. Act III Scene 1: (Brutus) "People and senators, be not affrighted. Fly not; stand still; ambition's debt is paid." As the audience realizes Brutus's perception is not as it should be, fear and pity are evoked, making him the tragic hero.
At the same time, idealism can be healthy. Realism, the cotrary of idealism can be harsh and cause unnecessary stress, where as a normal amount of idealism can make life much more pleasant. When everything seems to go your way it may be hard to make responsible decisions. Act III Scene 1: (Cassius) "Brutus, a word with you. You know not what you do; do not consent..." Had Brutus been more aware of what was really occurring, Rome may have been much more prosperous.
As a result of Brutus's lack of grasp on reality many innocent lives were lost. This is not a normal consequence of idealism, however it's an example of the possibilities. Act IV Scene 1: (Brutus) "Yes, Cassius, and from henceforth, when you are over-earnest with your Brutus, he'll think your mother chides, and leave you so." Consequently, the conspirators, destroyed the only man who could make calm from chaos, in Rome.
Brutus was tragically flawed with too much idealism. A certain amount of idealism may not be dangerous, but Julius Caeser displays what more could cause. By not just accepting things the way they are, Brutus wreaked havoc on the lives...