If he hadn't started with light beer drinking as the starting point, his life definitely would not have become ruined.

You are probably not an "addict type personality", without own experience regarding addiction ("As someone who never drinks alcohol"), speaking from a theoretical point of view. I don't. And I think there is a high probability his life would have become ruined anyway.

... addiction physical pathways in the brain....... the brain starts to get heavily programmed...... The addiction is completely physical of course

Absolutely not! This is a too narrow mechanical view of addiction. The addiction becomes also(!) physical, but someone who becomes addicted to [Cigarettes/Alcohol/Sex/Ayahuasca --- whatever] usually does so because he has mental problems.

Not seeing this is like when the husband/wife had an affair saying "it just happened... doesn't mean anything". Of course it did not "just happened" and does have a deeper meaning, indicating an underlying problem in the partnership, no matter how much both might be convinced that it is perfect. It's not - otherwise it would not "just happened".

Same with addictions: Usually one gets into them if there is an underlying non-physical reason. Result: Even if an addict to substance/behavior "X" manages to get rid of his addiction to "X": As long as the underlying reason persists, the mental problem behind his tendency, he is always in danger to become addicted to "Y" instead (because he needs(!) to be addicted to [whatever]) --- and to ruin his live.