How much does it cost an attacker these days to launch a large-scale attack? What's the going rate per Gbit of DDoS?
I'm guessing that the majority of major ISPs still allow outgoing traffic with spoofed IP addresses. If only politicians worked less to undermine security, and started mandating that ISPs install filters to block spoofed traffic instead of mandating that they spend money on filters to direct traffic to politicians.
All a bit depressing, really.