Fred Wilson, of Union Square Ventures, recently recounted on his blog, the story of his investment in Coinbase. 

"I like to tell the story of when I met Brian Armstrong, the founder of our portfolio company Coinbase in the summer of 2012. Paul Graham had asked me to do office hours at Y Combinator and so I came to their offices and spent four hours meeting sixteen companies in back to back 15 minute pitches. At the end of the four hours, I walked out of the conference room and Paul was waiting for me. He asked “which ones did you like best?” and I replied “I like Coinbase. I think Brian Armstrong is on to something big.” He was surprised and said “You are the first VC to say that.” And I said “Then its going to be huge. Please make sure we get the call when they want to raise.”

That’s negative social proof. When nobody else likes the deal but you. That’s how you win big."

He uses the story to highlight a broader point that you when big when you have interesting ideas that a lot of others don't agree with. 

A lot of advice falls in this category, where the salient elements from an experience from the past are extracted and then generalised.

But it is often the case, as it is with Fred Wilson's story above, that the elements highlighted are only necessary conditions and not sufficient conditions. 

Of course, Fred knows that and people giving out advice know that and they mean it that way as well. However, people consuming the advice don't often know that or tend to ignore the sufficiency part and dive right into following the advice. 

When something is a necessary condition, then without that condition being met, the outcome won't be achieved. In Fred's story, nobody liking the deal but him was a necessary condition. Otherwise, everyone would have wanted to invest in Coinbase, making it more expensive for him to invest in Coinbase and thus reducing the returns he would get on his investment. 

When something is a sufficient condition, then once that condition is met, the outcome is guaranteed. Which isn't the case in Fred's story. Just because nobody else thought it was a great idea and Fred did, wasn't going to be enough to guarantee a positive outcome for him. 

When you get advice, before you act on it, think about whether it is a necessary condition or a sufficient condition. If it is necessary but not sufficient, there is more that you need to do.