I would think very hard about hiring or investing in someone who used marijuana, or who decided to sell marijuana (a bet with a big risk for very little reward), or who thought that using drugs was cool enough to include it on an application. Speaking from experience, marijuana is addictive, saps ambition, and makes it difficult to think hard and think logically. Anyone who has tried to code or do math while high knows exactly what I am talking about.
Wesley, obviously you have grown and been very successful since. I wish you only more success, and you are already far ahead of where I was at 19 (still smoking too much pot).
The difference is that I think very few people would say "Let's remove the stigma from alchoholism."
For me, I really don't give a damn what kinds of drugs people take beyond heroin, crack, meth, and others that have a clear history of detrimental effects on the individual. As long as you are rock solid and reliable, that's all that matters.
If you can be sure that someone is reliable, then you are right, there is no reason to have a problem with their drug use. When you are hiring someone or making the decision to invest money with them, you rarely know enough to be sure. Using drugs is a HUGE red flag there, and should say think twice before hiring this person / giving them money.
I don't think drugs are incompatible with being a responsible and productive person. There would be downsides to high profile drug use, like what happened to Sean Parker at Facebook, where presumably there was fear that the LPs in various investors would raise issues.
People can be useless fucktards with or without drugs; people can be productive with or without drugs.
Pot isn't the worst thing ever, but it isn't going to help you start a business or become a great programmer. While you are high, you will be worse at reasoning and your working memory won't be great. This makes it harder to write code. There is also a legal risk, justified or not.
Drugs are a frustrating topic to debate. On one side there is a huge amount of misinformation intended to scare people away from drug use. Then, in reaction to that and coming out of the cognitive dissonance of millions of people doing something that they know isn't good for them, there is a ton of 'pot is good for you because it comes from the earth' bs on the other side. I think people on the internet (and apparently on HN) tend to be in the latter group, and I feel like it is worth pointing out the downsides.