The relevant point of your link is "We find that alcohol consumption fell sharply at the beginning of Prohibition, to approximately 30 percent of its pre-Prohi

The relevant point of your link is "We find that alcohol consumption fell sharply at the beginning of Prohibition, to approximately 30 percent of its pre-Prohibition level. During the next several years, however, alcohol consumption increased sharply to about 60-70 percent of its pre-Prohibition level." If I was trying to prohibit something but could only manage to prevent 30-40 percent of it compared to when it was legal I would certainly feel I had failed. This is without factoring in all the other problems Prohibition caused.