I'm going to attempt something a little odd today, Fools. Even though Amazon.com (NASDAQ:AMZN) is by far the largest of my real-life holdings -- at 11.4% of my family's portfolio -- and I've said many times that Amazon is my highest conviction holding, I'm going to be giving you three reasons to consider selling Amazon stock today.

Why am I doing this?

Recently, Nobel Prize winner Daniel Kahneman visited Fool headquarters in Virginia. While visiting, he talked about how a number of different biases can lead us to believe we can predict the future with relative certainty. In reality, he argued, we're just deluding ourselves.

It got me to thinking about how I don't write enough about the risks of owning the stocks I own. So although I don't plan on selling my Amazon stock anytime soon, I think it's healthy for me to practice and model this behavior.

Let's go over the three points.

1. Minuscule profits, expensive stock
Amazon is the undisputed leader of e-commerce, which still has tons of room for growth. In 2012, the company brought in $61 billion in sales. The company can deliver everything from furniture to food to your front door lickety-split, and it pioneered the popularity of e-books.

Yet despite this dominance, Amazon actually hasn't even turned a profit over the past 12 months.

Why is this the case? There are really two reasons.

First, the company offers goods for razor-thin margins to secure its station as the go-to website for e-commerce. Amazon Prime offers an amazing deal to subscribers for shipping purposes, and Amazon loses a bundle of money every year as a result.

Secondly, the company is aggressively spending to build out fulfillment centers and invest in technology that CEO Jeff Bezos believes will lead the company forward.

All of this spending has led Matthew Yglesias at Slate to quip: "Amazon, as best I can tell, is a charitable organization being run by elements of the investment community for the benefit of consumers." 

Right now, the stock is priced on expectations that eventually, some day, the spending will drop and profits will absolutely soar. That's a lot to assume, and if it doesn't turn out that way, Amazon stock will absolutely crash.

2. A single-man empire?
I love the fact that Amazon has some pretty sustainable competitive advantages -- both in terms of the network effect it has established, and the build-out of crazy-expensive fulfillment centers to deliver products to customers ASAP.

That being said, a constant focus on customer service -- and continued innovation around this principle -- is why I'm invested in the company. The primary driver behind this customer service focus has been Bezos. There's no telling if the next CEO will have the same approach, and that strikes right to the core of what makes Amazon, Amazon.

Futhermore, Wall Street has been very patient in allowing Bezos to trade short-term profits for long-term dominance, but if someone else were to take the helm, that trust could disappear overnight, sending shares tumbling.

3. Out innovating the innovator?
I'll admit that my final concern might seem a little far-fetched. But for decades-long investors, it's worth considering.

The reason Amazon has been so disruptive over the past 15 years is that it offers something easier, more personalized, and more convenient than what was previously available. You can get exactly what you want delivered to you in 48 hours, and all you have to do is click a button.

But what if you didn't even have to wait that long, and you could get more personalized products? While it's still in its infancy, that's the type of disruption that could be headed our way via 3-D printing.

It seemed ridiculous in the '80s to say that everyone would own a desktop computer, but it basically happened. While it might seem ridiculous today to say that every home will have a 3-D printer, that doesn't mean it won't happen.

If it does, consumers can cut Amazon out of the picture, download the necessary files from the Internet, buy the necessary inputs for their printer, and print out what they want right from home.

Though I don't plan on selling my Amazon stock anytime soon, the threat from 3-D printing companies is one I'll be keeping a close eye on. It's also why I own two of the biggest names in the industry in my real-life holdings as well. To find out what these two companies are -- as well as an additional, underappreciated 3-D player -- check out our special free report: "3 Stocks to Own for the New Industrial Revolution." Just click here to learn more.

Fool contributor Brian Stoffel owns shares of Amazon.com. The Motley Fool recommends and owns shares of Amazon.com. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.