Insecure driver + giant metal cocoon + yuppies in spandex + zero driver context about cycling + Texas = the video you see here. Some people literally lose their minds where they're in a car and see a yuppie wearing spandex. They can't take it and react in unpredictable ways.

I'll make some guess about these drivers' mentality:
They believe cyclists are insane.
They believe that they are being inconvenienced by lawbreaking cyclists who have no "right" to be on the road.
They don't get why cyclists "have to ride in groups".
They don't get why cyclists don't constrain cycling to sidewalks and bike paths.
To them, cyclists are possibly gay weirdos who wear superhero costumes while riding around on toys and aren't man enough to do a "real sport".

Cyclists become inhuman in their minds. They're not real people and don't deserve to be treated with respect or even safety. If cyclists die, they had it coming.