"Life is hard, but I am harder."
Translation:Het leven is hard, maar ik ben harder.
A better translation might be "life is tough, but I am tougher". You might also come across "de harde werkelijkheid" which means something like "the bitter reality". There is also the expression "hard tegen iemand zijn" which means "to be strict against [with] someone".
I think "het leven is hard, maar ik ben harder" is a pretty common wordplay though maybe more so among younger people.