(By Nate C. Hindman)

“We made the classic mistake that all investors make,” Wilson recalled in a blog post lamenting the blunder. “We focused too much on what they were doing at the time and not enough on what they could do, would do, and did do.”

Even the most well-known venture capitalists have startups they regret passing on.

For John Doerr of Kleiner Perkins, it was Twitter. For Fred Wilson of Union Square Ventures, it was Airbnb, the home-rental website that’s now worth an estimated $2.5 billion.

“We made the classic mistake that all investors make,” Wilson recalled in a blog post lamenting the blunder. “We focused too much on what they were doing at the time and not enough on what they could do, would do, and did do.”

It’s hard to blame him. After all, a lot of successful companies sounded stupid when they first launched — see: Rap Genius — and the vast majority of new businesses flop, sometimes leaving investors with heavy losses.

But before you write off a fledgling firm, always keep in mind that you never know.

Here are the 18 most ridiculous startup ideas that eventually became successful, named and explained by Pipewise CEO Michael Wolfe on Quora:

1) Facebook

The world needs yet another Myspace or Friendster, except several years late. We’ll only open it up to a few thousand overworked, anti-social Ivy Leaguers. Everyone else will then join since Harvard students are so cool.

2) Amazon

We’ll sell books online, even though users are still scared to use credit cards on the web. Their shipping costs will eat up any money they save. They’ll do it for the convenience, even though they have to wait a week for the book.

3) Virgin Atlantic

Airlines are cool. Let’s start one. How hard could it be? We’ll differentiate with a funny safety video and by not being a**holes.

4) Craigslist

It will be ugly. It will be free.

5) Google

We are building the world’s 20th search engine at a time when most of the others have been abandoned as commoditized money-losers. We’ll strip out all of the ad-supported news and portal features so you won’t be distracted from using the free search stuff.

6) Tesla

Instead of just building batteries and selling them to Detroit, we are going to build our own cars from scratch plus own the distribution network. During a recession and a cleantech backlash.

7) SpaceX

If NASA can do it, so can we! It ain’t rocket science.

8) Twitter

It is like email, SMS or RSS. Except it does a lot less. It will be used mostly by geeks at first, followed by Britney Spears and Charlie Sheen.

9) Paperless Post

We are like Evite, except you pay us. All of your friends will know what you’ve been up to.

10) Instagram

Filters! That’s right, we got filters!

11) PayPal

People will use their insecure AOL and Yahoo email addresses to pay each other real money, backed by a non-bank with a cute name run by 20-somethings.

12) LinkedIn

How about a professional social network, aimed at busy 30- and 40-somethings. They will use it once every 5 years when they go job searching.

13) Mint

Give us all of your bank, brokerage, and credit card information. We’ll give it back to you with nice fonts. To make you feel richer, we’ll make them green.

14) Dropbox

We are going to build a file sharing and syncing solution when the market has a dozen of them that no one uses, supported by big companies like Microsoft. It will only do one thing well, and you’ll have to move all of your content to use it.

15) Palantir

We’ll build arcane analytics software, put the company in California, hire a bunch of new college grad engineers, many of them immigrants, hire no sales reps, and close giant deals with D.C.-based defense and intelligence agencies!

16) iOS

A brand new operating system that doesn’t run a single one of the millions of applications that have been developed for Mac OS, Windows, or Linux. Only Apple can build apps for it. It won’t have cut and paste.

17) GitHub

Software engineers will pay monthly fees for the rest of their lives in order to create free software out of other free software!

18) Firefox

We are going to build a better web browser, even though 90 percent of the world’s computers already have a free one built in. One guy will do most of the work.

(Source: Huffingtonpost)

“Opinion pieces of this sort published on RISE Networks are those of the original authors and do not in anyway represent the thoughts, beliefs and ideas of RISE Networks.”