Because you reap it's benefits, as do I, and the pittance that we both would offer in return is the least either of us could do, although I wouldn't fault you for feeling obligated to do that little bit more. We all live off each other's backs and always have done. The only real individual contribution any one person can make to this world is to share that load with others whose knees are quaking under the weight. You can call that a welfare state all you like, I'd just as soon call it living in a society.
If you want to make the numbers work (faith is the only way to redemption), just de-fund the military industrial complex, stop heavily subsidizing fossil fuels and agribusiness, institute and enforce global antitrust and more stringent Glass-Steagall style legislation worldwide (as if), ban derivatives (ezpz), forgive all Greek debt, and tax the fuckers who stole the rugs from under our collective feet to all oblivion. All currency is the property of its respective state, so start treating it that way. End this hell-bound neoliberal experiment. But that's certainly crazier than watching thousands of people suffocate and drown at your doorstep while starving, murdering, and/or persecuting those they left behind.
What makes it all that much worse is that you'd only need to do .00000001% of this communist nonsense to come up with the cash (if any, really). But its never really been about the money, has it?