Vicious circle of karma

My question is: as i understand if you are a bad person in this life you pile up a ton of negative karma which will lead to miserable circumstances in the next life like cruel parents, birth in the poor country and that entails bad upbringing. In the end we will get even worse person then in the previos life (some street thug) who will accumulate more bad karma and so on. How do a man break out of this vicious circle of karma?