Sometimes, success seems so counterintuitive, it's nearly impossible to figure it out. Take, for example, Pinterest founder Ben Silbermann, the wildly successful visual social networking entrepreneur who amassed $100 million before his 30th birthday.

There are a lot of reasons why, according to traditional start-up wisdom, he should not have succeeded. Of course, the man is brilliant, but it would have been impossible to predict that he would succeed as a tech founder if you'd met him even five years ago.

Yet did he ever! Expected to go public next year, Pinterest is one of an elite group of 40 U.S. venture-backed, pre-IPO tech firms valued at over $1 billion.

Silbermann's story should inspire even the most self-doubting of entrepreneurs. It proves you don't necessarily need the right college, the best concept, or the perfect start-up strategy right out of the gate. There's this almost destructive belief in Silicon Valley tech crowds (and to a lesser extent, the East Coast crew) that if you haven't launched a super successful start-up by your mid- to late 20s, you've failed.

It's just not true. Check out the crazy, unexpected path to success Silbermann blazed. Here are four reasons he should be totally broke right now.

He had no engineering background, yet jumped into the tech scene.

Engineering is highly valued in tech start-ups, so much so that some companies have an almost exclusive engineering focus in early days. After all, you have to be an engineer to build anything cool, right?

Silbermann went to Yale, but few know that he actually studied pre-med, not engineering. He was also really interested in political science and graduated in 2003 with a BA, not a BEng or even a BS. Interestingly, none of three co-founders of Pinterest are engineers, which is pretty rare for a tech start-up.

He quit his job at Google.

Is he crazy? Google is a dream employer for a ton of innovative 20-something, fresh-faced college kids.

After graduating college, Silbermann landed a consulting job in Washington, D.C., where he was placed in the Tech Group because that's where the open positions happened to be. His work in corporate IT infrastructure was his introduction to the fast paced, ever-changing world of technology--and he was hooked.

From there, he went straight to Google in 2006, where he would stay for two years as a product specialist working in the display ads group. In a 2012 Startup Grind interview, Silbermann describes his time at Google as super exciting and cool; he felt fortunate, but was frustrated because he lacked that engineering background.

He'd been talking about starting his own business and in 2008, Silbermann's girlfriend challenged him to put up or shut up. They were in California, she pointed out--why couldn't he just go for it?

And with that, Silbermann quit a job many would kill for. His timing was terrible; it was the year Bear Sterns collapsed; funding opportunities in the next few years would be fiercely competitive and hard to come by. As he said, "I didn't have a fully baked plan. I just left."

His first start-up was a flop.

Silbermann kept working away at the side jobs he'd started during his time at Google, but ended up back in a biology lab with some of his college friends. He worked on an iPhone app with another friend from school, who was all the way across the country working in New York. His name was Paul Sciarra.

In the back of his mind, though, Silbermann had an idea for a website that was built around collections (he'd been an enthusiastic collector as a child). He discussed his idea with friend and architecture graduate, Evan Sharp.

Yes, that Evan Sharp--the third co-founder of Pinterest. Doesn't it seem serendipitous how these things can come together?

Silbermann got Sciarra and Sharp interested in his collection website idea and they decided to give it a shot. As soon as they had a prototype, they got moving on trying to fund it.

He was rejected by multiple investors.

Times were tough and even future multimillionaires certainly were not immune. He says of that time, "We did the tour, we met with everyone, I mean everyone who would take a meeting, I would cold call people out of alumni directories, we met with everyone."

I totally understand how this can make an entrepreneur feel, having received my fair share of rejection letters in WordStream's early days. It can be incredibly discouraging; a lot of start-up founders hear one rejection too many and give up.

Silbermann and his co-founders didn't give up, though. As he explained, it would be too embarrassing to have to go ask for his job back. He was all in.

And it's a good thing he was, alongside his co-founders! Pinterest now boasts over 70 million users and is growing steadily in the global market. Their tests with advertising options hold great promise for advertisers and future investors alike.

Ben Silbermann's path to success was loaded with potential entrepreneurial landmines, yet he beat the odds to help build one of the most successful social networks of our time--and made himself a multimillionaire in the process. What's standing in your way?