I don't think that's true. They certainly knew about the iPhone before the public did, and so they had a ton of time and money to position themselves for it. Certainly the iPhone was a game changer, but there is absolutely no reason that a better managed RIM shouldn't have come out ahead. Look up some of the stuff that Lazaridis said about the iPhone.
I mean, read this: http://www.guardian.co.uk/technology/2012/jun/29/rim-chiefs-... . The iPhone didn't kill RIM, it was hubris and complacency.