According to Bloomberg, 8 out of 10 entrepreneurs who start businesses fail within the first 18 months. A whopping 80% crash and burn.

But why? What can we learn from the colossal amount of failure with small business that we can apply to our own business aspirations? At surface level the primary reason businesses fail is they simply run out of cash.

The cracks in the foundation start well before the brutal day of financial collapse. Here are the top five subsequent reasons why small businesses fail.

1: Not really in touch with customers through deep dialogue.

An amazing thing happens when an entrepreneur sees a potential opportunity in the market, or dreams up a new idea for a product/service: they retreat to a cave.

In my experience, this is the worst move an entrepreneur can make because complete understanding of your customer is imperative to your success. Listen — in my mind entrepreneurs must walk 1,000 miles in the shoes of their customers. Not 10. Not 100. One thousand.

Your customer holds the key to your success deep in their pain, behavior, dreams, values and the jobs they are trying to accomplish.

2: No real differentiation in the market (read: lack of unique value propositions)

Entrepreneur.com just put out a story entitled “Why Everyone Will Have To Become An Entrepreneur”. If this holds true (and I think it will), instead of your competition being 5,000 other Tom, Dick and Harrys, it will soon be 50,000 of these guys.

Meaning? Plenty of noise and chaos for those without uniqueness fighting for the bottom scraps. Most times this is a slow killer of businesses. Barely hanging on, entrepreneurs with some customers and some revenue skimp along for months or even years. Every painful inch wondering to themselves if this is all there really is.

3: Failure to communicate value propositions in clear, concise and compelling fashion.

Next up is the debilitating disease called ‘failure to communicate’. For those old enough to remember the classic 1967 Paul Newman movie ‘Cool Hand Luke’, seared on the brain is a key line spoken by the prison warden to Newman who plays the maddeningly defiant inmate named Luke. “What we have here is a failure to communicate…”, upon which Newman is shot in the neck and on his way to exsanguination (aka bleeding to death).

Many entrepreneurs work hard to discover a point of differentiation then blow it because they do not communicate their message in a clear, concise and compelling manner. I watch many entrepreneurs bleed to death through their failure to communicate.

4: Leadership breakdown at the top (yes — founder dysfunction).

You see it all the time in the media. Right off the deep end goes another athlete with unbelievable talent. Painful to watch the self-sabotage of the likes of a Lance Armstrong, Mike Tyson or Aaron Hernandez, all of which fell short from truly remarkable success because of their poor decisions.

Now startup entrepreneurs who go down hard might not have their names splashed across the headlines of tomorrow’s New York Post, but I submit to you their reason for failure is sometimes the same. Self-sabotage through extremely poor decision making and weak leadership skills.

5: Inability to nail a profitable business model with proven revenue streams.

In the end, this is the sum total. Fail to accurately achieve product/market fit where money gets made, and you’re sunk. Entrepreneurs can actually have each of the four above reasons solved, but still miss the business model boat. Twitter is a perfect example of this.