I think part of the problem is that with modern cars it's very easy to drive quickly in them. I think a lot of people are overconfident in their driving ability and the ability of their car, until they suddenly find the difference between 7/10ths and 10/10s. I drive a lot of back roads on my daily commute, and you'd be amazed at how many drivers are driving their cars at 7/10ths and above (especially in wet conditions).
I follow a lot of these people (from a safe distance) and I think to myself - "Do they have any idea they're one surprise away from sliding right off the road?"