They gambled on a profit-less company IPO and lost. I'd say there was some hindsight.
ALso, 500M is a lot of money but it's not THAT much money when you're running a multi-billion dollar company and responsible for delivering billions in revenue. To get those numbers you have to invest in things. NBC isn't sitting around wondering if they can eek out another million dollars of ad buys for the TODAY show this quarter.