Unless you've driven / been a passenger in a very powerful car, you can't imagine what it's like. You can get to 100MPH from a standstill in a CGT in around 7 seconds, and if you're already doing 30MPH and put your foot down for a few seconds, that's all it'll take.
I'm pretty sure that the vast majority of people on this forum would do exactly the same at some point if they could afford a car like that, in fact, I'll bet a lot of us have done similar things in considerably less capable cars, and were just lucky to get away with it.
It seems like the driver was experienced, and Paul probably trusted him to do those speeds, but that day he happened to make a mistake which resulted in their deaths. Nothing more to it than that I reckon.