Has this happened to you or another founder? Someone invests in your company to gather information which they use to help a competitor launch a competing product?

I'm the OP guy. Read the article. Two years ago the founder of Postmates approached the founder of Uber to let him know that he's a fan and the founder of Uber said, "See you in the trenches.", which means that he was already planning on competing with Postmates two years ago, which is before the Uber investor invested in Postmates.

You think that the Uber founder didn't plan it all out to spy on Postmates and gleam information from them through mutual investors?

I don't. Occam's Razor.

In that case, why wasn't Postmates more selective in choosing their investors? Ie, don't accept $$ from a guy already invested in your potential rival.

Says right in the article. The founder of Postmates thought that if his company and Uber shared the same investors that they were unlikely to launch a competing business.

So, he saw it as a defense mechanism, but really all it did was lull him into a false sense of security.

Not really. Individual investors don't tend to contribute much in funding rounds; usually in the range of $50,000-$200,000, and the round was I believe $6 million. So, it's chump change compared to the value of his shares in Uber, which will grow if they can expand their business by launching a competing service to Postmates.

By the way, I'm the OP.

Yes. I think their culture of corruption starts at the top with the CEO. He's a douchebag. He denies any customer accusations of misbehavior on the part of Uber drivers.

The whole sharing economy startup scene is a scam. Using googles tried and true don't be evil speak but targeting regulation instead of Microsoft. I can't stand those mofos.