This is a subject that has often been a topic in my house. On both of the tours we did, the other participants not only drank ( a lot) at the lunch stops, but also drank copious amounts at the dinners. On the last day of my tour in Austria, several did a "beer tasting" crawl on the bike path.
My husband and I were like social outcasts. Now, I drink, but I see drinking and riding as the same as drinking and driving. I couldn't ride after one glass of wine. Plus, drinking is a horrible dehydrator for me. The next morning I have to over hydrate just to make up for 1-2 glasses of wine. So these people were able to deal with all of that and ride 30-50 miles a day on huge climbs.

We did not drink at least 2 of the 6 nights and were always the first to go to bed. I need sleep, good food and proper hydration to do streneuous riding. Perhaps I'm a wimp, but our friends we ride with all of the time are even worse.