The poor chap is possibly suffering from stress over work and his drinking is helping him cope with the strains of his job,possibly his partner is getting upset at his long hours,and giving him greif at home, his kids have become unruly as he doesnt have time to spend time with them,he works hard to support his wife and kids, and give them a good standard of living , his heavy drinking all helps above relieve his stresses.
Thats what drunks usually say.
Then due to his drinking he injures or kills someone, real and deep stress then affects all those involved, those who didnt report him, those who could have warned him about his drinking etc.
Just report him and get the “piss head” off the road. Every little helps.