Prohibition wasn't an abject failure. The most pessimistic reading is that its results were mixed, with many scholars believing it was a success. (There was a reason it took 14 years to repeal and not because people thought it was an abject failure.)

Copied & pasted from Wikipedia:

"Alcohol consumption declined dramatically during Prohibition. Cirrhosis death rates for men were 29.5 per 100,000 in 1911 and 10.7 in 1929. Admissions to state mental hospitals for alcoholic psychosis declined from 10.1 per 100,000 in 1919 to 4.7 in 1928. Arrests for public drunkenness and disorderly conduct declined 50 percent between 1916 and 1922. For the population as a whole, the best estimates are that consumption of alcohol declined by 30 percent to 50 percent.[7]

Specifically, "rates for cirrhosis of the liver fell by 50 percent early in Prohibition and recovered promptly after Repeal in 1933."[4] Moore also found that contrary to popular opinion, "violent crime did not increase dramatically during Prohibition" and that organized crime "existed before and after" Prohibition.[7] The historian Jack S. Blocker Jr. stated that "Death rates from cirrhosis and alcoholism, alcoholic psychosis hospital admissions, and drunkenness arrests all declined steeply during the latter years of the 1910s, when both the cultural and the legal climate were increasingly inhospitable to drink, and in the early years after National Prohibition went into effect."[8] In addition, "once Prohibition became the law of the land, many citizens decided to obey it".[8] During the Prohibition era, rates of absenteeism decreased from 10% to 3%.[9] In Michigan, the Ford Motor Company documented "a decrease in absenteeism from 2,620 in April 1918 to 1,628 in May 1918."[6]