He showed them alright

This kind of poor judgement doesn't just happen once out of the blue. This driver probably has a trail of bad decisions leading back to childhood.
In other words he was a ticking time bomb, and alcohol was the catalyst. If anyone mentioned it to him he probably punched them in the mouth.

What bothers me the most is how he was allowed to get behind the wheel of an 80,000 lb. device. It's a rhetorical question, there are individuals in all occupations who are just as mal adjusted, cops, dentists, judges, etc. Mental health issues are real, and with modern social media (he texted his intentions multiple times before he did it) amplifying his self validation, this sort of behavior is getting worse by the day.
No significant prior criminal record, now in his 30's who gave it ALL up to spend life in a cage for the next 40-50 years.

Learn from his experience. If you see someone with similar self destructive behavior, either stay out of their way, or if you care, intervene. With caution.