A sincere question for Atheists?

Will all the billions of rapists, terrorists, murderers, pedophiles, that have lived but never got caught by the law will ever pay for what they did? If only death is standing at the end of life with open arms then it doesn't really matter if one lives like Hitler or like a Saint, so why even restrain yourself from any pleasure, or live by rules? Life is way to short not have it any other way.. And one might say, its for further generations well the universe is expanding and will eventually be sucked into a black hole, therefore all technological advances, scientific discoveries, personal achievements along with the earth, will eventually be swallowed up by the same cosmic space that coughed it out, so even in the overall scheme of things, nothing absolutely nothing even matters, it will all be forgotten. So basically the qualitative value of human life is no more than that of a fly, after all we are the result of blind chance, a cosmic freak accident... So atheists why do you have morals? And lets be clear morals are not scientific, some people say its so but again why would you deny yourself pleasure so that someone else can be okay? Thats not scientific, Morals are not even scientific, when a lion kills a gazelle its exactly that, killing a gazelle but its not considered murder. Not trying to argue but I seriously want to know that if at death it doesn't make a difference if you lived like Hitler or a Saint, if you were a faithful husband or a pedophile why have any rules at all thats the million dollar question. And whats your justification for having them because to NOT have them is the only logical thing to do...