That sounds completely backwards to me. Big companies get disrupted because they are too locked-in to milking their current cash cow, and they either don't see - or consciously choose to ignore - any threat to that cash cow. It's more like a case of myopia combined with tunnel-vision, IMO.
Meanwhile, scrappy upstarts are experimenting and trying new ideas, find a better new approach, and can launch it and start growing it, while $BIGCORP remains blissfully unaware, until it's too late. Basically, the classic Innovator's Dilemma situation.
And while $BIGCORPs often ignore disruptive innovations even when they develop them themselves, it still seems to me that you're better off to be the one developing the disruptive innovation yourself, so you at least have a shot at adapting before somebody else comes along and takes your lunch money.