The fact that big-bang innovations combine pre-existing technologies that don’t even seem related to your offerings to achieve a noticeably better value proposition poses perhaps the biggest challenge to incumbents. Big-bang disruptors might not even consider you to be a rival. They don’t approach customer needs in the same way that you do.
Most of the time, they’re just throwing something flashy in your customers’ faces in an effort to entice them to a company that is entirely unrelated to yours.