Why do you think governments want to influence the supply of alcohol and tobacco products by imposing excise taxes?

So that the government earn more revenue .Few governments for exampe India people are still ready to pay high to consume alcohol and tobacco,So therefore Indian government charges high tax(not too high) so that the consumers doesn't decrease their consumption and increase the government revenues to reduce the consumption .if taxes are high people might refuse to buy tobacco and alcohol thus reduces the consumption

Yes it's true they get dissatisfied