Of course sin taxes work. You might think that is up to a person to decide whether to smoke or drink, or eat sugar. But in the end ppl end up in hospitals and health care ministry has to cover all the bills. Especially in countries that has free medical care. Where as this money could be used elsewhere -to build new roads, improve education etc.
One thing with sin taxes is that people will peradventure find a way to just simply cut back on some things and then find a way to readjust, but does not necessary curtail the consumption of such things directly.
Most of the time, it still all falls back on the consumers anyway and one thing for someone who is already addicted, they would always go even above themselves to do whatever they are craving for. So, does it necessarily work, maybe on just few people that can do without it.