Well that’s exactly what happens; double the price of something and demand / sales drops significantly. Here,wine is significantly overpriced (about double the UK price for an Australian example ) so I don’t drink it (or extremely rarely) so net tax intake is nil. Reduce the taxes and I (and many others) will drink more. There’s basically a curve (like the Laffer curve) where the tax rate optimizes the total tax take. Thailand is way past the top of the curve on the downward slope so shooting itself in the foot.