The answer, unfortunately, is that alcoholism is a severe mental illness caused by a chemical imbalance within the brain. Just like anyone else with any kind of mental illness, such as anyone suffering from depression, stress or an eating disorder, an alcoholic is completely unable to simply ‘shake it off’ and stop drinking.
That’s the simple explanation, but for a more scientific answer, see below:
In a normally functioning brain, chemicals called neurotransmitters help the brain to communicate efficiently with every other area of the body.
Once someone starts drinking, this interferes with the balance of the brain and affects the neurotransmitter pathways. The ethanol in an alcoholic drink suppresses glutamate, an excitatory neurotransmitter, causing slurred speech and lack of co-ordination. The main inhibitory neurotransmitter, Gamma-aminobutyric acid (GABA) is also affected by ethanol and is responsible for that feeling of wanting to drop off to sleep. Dopamine and serotonin release is also stimulated by drinking alcohol, and these neurotransmitters are what creates those feelings of being happy, excited and euphoric that the drinker can begin to crave.
Over time, less dopamine is released, and it takes more alcohol to get the same feelings of excitement and euphoria, and this can lead to alcohol addiction, with the accompanying withdrawal symptoms as the brain gets used to having alcohol present.