Because nobody can feel the way you feel. No one will feel your pains, they have their own share of pains to feel. No one will feel like you until they start walking on the path you've trodden, in your shoes not theirs and relive those moments which broke you from deep inside. No one will understand that weird feeling which is unexplained untill they imbibe your soul and exchange bodies with you.
And so the hope of venting off that frustration, that dire need of satisfaction which you think you'll get in return by cursing or hitting someone will be unachievable as your inner monster will never be gratified and won't stop chasing you. It will not remove that strange, unexplainable feeling. It will not save you. Instead it will do the opposite..
It will destroy you. It will crush your already broken pieces that they can never be put together. It strain your relationship with your loved ones. It will make your head throb in pain. It will make you feel sick and ruined.
How much widespread will be the disease of your pelt up frustration? How many people will suffer from that diesase and work according to your whims and fancies? And you know what's worst? You don't blame yourself for any of it, you deny to accept that the problem is with you. If you hate something it because of another person. If you don't understand anything its the fault of the other instead of your own. Why this happens? Due to those demons which exist within you, they make you see things in a way which are absolutely flawless when in reality they are not, they make you fight but yet you're not the one to be blamed.
And all this occurs when you water and nurture your bitterness, your frustration, your resentments and hatred. You harbour ill feelings and those get converted into discontentment towards your own life, it hinders your growth. The bucket of negativity keeps filling in until the brim and then it starts exuding those negative vibes. The nurtured sapling of hatred grows into a large tree growing extensively and spreads it roots afar. This causes harm, an unimaginable loss which courses through gradually and poisons your soul.