The F1 cars were on the wrong tyres for the weather. They have three different ones Wet tyres have a deep grooves. Intermediates, a medium groove. Dry, very little grooving.bearing in mind the amount of water on the track, and the drivers were on dry tyres, plus the speed, it is little wonder that they were able to keep a line at all.
The section where they were coming off, was a downhill run plus a right turn, normally a section where they would have to be doing heavy braking.
Try that wet or icy conditions at speed.I had a similar experiance a few years ago, one end of my street has a sharp right turn and a downhill. The road was covered in ice, I approached the corner at less than walking pace, turned the wheel, and just kept going in the same direction, into a parked car, nothing I could have done about it. The contact was so soft, no damage, and I pushed my car sideways away and continued my journey.