Some think Tesla is a tech company, but its main product is cars, so it effectively exists in the auto industry.

For years, auto sales have boomed in the US and automakers have raked in profits while Tesla has lost billions.

Unless Tesla reverses this trend, it won't be able to weather a downturn when sales drop and profits vanish.

Optimism and skepticism about Tesla's future are in an all-out war. Those who are bullish on the 15-year-old maker of sexy all-electric cars are doubling down on their bullishness and support for CEO Elon Musk.

Those who are bearish are predicting a bankruptcy in the next year, as Tesla burns through its cash and fails to persuade new investors to fund its monumental losses — something like $20 billion for the life of the company.

Tesla, at its base, is an automaker. But unlike other automakers, Tesla is valued like a rapid-growth tech firm and avidly followed by the same enthusiasts who might consider their passions to be social media, fintech, and cryptocurrencies.

Meanwhile, there's a traditional auto industry that, after being pummeled by the financial crisis, has come roaring back since 2010. The four old-school companies I follow closely — General Motors, Ford, Fiat Chrysler Automobiles, and Ferrari — are awash in cash and profits and have been raking it in for literally years.

One salient statistic: GM and Tesla staged initial public offerings in 2010, but since then Tesla has never posted an annual profit, while GM has made over $70 billion.

Shares of GM and Ford have performed poorly relative to the overall markets while Tesla has massively rewarded risk-taking investors. Since its IPO in 2014, FCA has rallied strongly, with shares up almost 275%, and since Ferrari's spinoff and 2015 IPO, shares of the Italian supercar brand are up 140%.

Those returns have been relatively riskless, while Tesla's certainly haven't. And even if you bought Ford and GM expecting better results, both companies have compensated investors with robust dividends and share buybacks.

Tesla bulls will tell you that to properly understand the potential of the company, you have to rearrange your thinking. Musk is a disruptive visionary; the cars are rolling computers.

That's fine for a jazzy storyline, but Tesla's struggle isn't related to its narrative — it's falling short on fundamentals, such as effectively building a midsize sedan in the Model 3. Any other established carmaker could crank out hundreds of thousands in short order, but Tesla spent a closely watched year trying to manufacture a few thousand per week.

So let's take a closer look at how Tesla is terrifyingly different from a regular car company.