Dustin Curtis recalls his first exposure to Pinterest and Vine:

In late 2009, I received an email from a guy asking to meet about his new project. I was a designer at the time, and he was looking for some advice, so I agreed to meet with him at the quintessential startup meeting place in San Francisco, The Creamery.

“I want to make an app for browsing catalogs. It's like a fashion catalog, but you can organize and share outfits,” he said. He pulled out his iPhone and showed me a prototype that barely worked. The UI was decent but clunky; it had side-swiping navigation that only worked every few swipes. He showed me what seemed to be an endless series of women's dresses. “Nice,” I said. But I had already dismissed the idea. How on Earth would this 20-something guy in Silicon Valley reach his target market of middle aged women? And would they even want such a thing? Did they even own iPhones? I think I asked a series of questions, but I don't even remember the answers.

“What a stupid idea,” I thought to myself.

As we finished our coffees, I think he sensed my apathy, and we parted ways. But just before I walked away, he asked a question:

“What do you think about the name we've been using? It's called Pinterest.”

In 2012, I met a guy for dinner at an unassuming restaurant in New York. After we'd started eating, he handed me his phone and said, “I'm making an app that makes it easy to share video, kind of like Instagram.” The app was very well designed and engineered, especially for a prototype, but I've had a lot of experience with photography and video apps, and I knew the odds were hugely against him. The mobile video space is littered with the dead carcasses of previous attempts. How would this guy overcome all of the hurdles that the plethora of other attempts at mobile video have been unable to address?

The app had one awesome feature, though–it would only record when your finger was on the screen, so you could take a bunch of little videos through time and connect them together to build a story. But it was a self-contained app, with its own feed and no obvious viral mechanics. I couldn't see it ever succeeding.

“What a stupid idea,” I thought to myself.

I liked the logo, though. It was a V on a green background, for the name “Vine.”

Thinking back on those meetings with Ben Silbermann, the founder of Pinterest, and Dom Hoffman, the founder of Vine, I am kind of disgusted by my reactions. Both of those guys are unusually passionate and driven, and you can tell within five seconds of meeting them. They saw the future and they built it. But for some reason, my first reaction to their earliest attempts wasn't to give them the benefit of the doubt–it was to immediately find problems and then dismiss their ideas.

The future is extremely hard to see through the lens of the present. It's very easy to unconsciously dismiss the first versions of something as frivolous or useless. Or as stupid ideas.

Hacker News discusses how success is not the validation of an idea:

https://news.ycombinator.com/item?id=5635437