It is true that currently thousands of people are employed by the alcoholic drinks industry. However the fact that an immoral industry employs a lot of people is never a good argument to keep that immoral industry going (similar arguments apply to the cases of prostitution, arms dealing, fox hunting, battery farming, etc.) Instead, a gradual process would have to be implemented, which would include governments providing funding for training for alternative careers.  Also it is true that tax revenues would be lost if alcohol were banned. However, again, this is not a principled reason to reject the proposition, simply a practical problem. It should be pointed out that governments would save a huge amount of money on police and health spending (through the reduction in crime and alcohol-related illness) which would go at least some of the way to offsetting the decreased tax revenues.