As HubSpot co-founder Dharmesh Shah says, "Success is making those who believed in you look brilliant."

By that definition, people who believed in Tesla -- or, more to the point, in Elon Musk -- look, if there is such a thing, incredibly brilliant: Tesla stock is up a staggering 700 percent this year. (In comparison, the Nasdaq is up a hefty 40 percent and the S&P 500 is up just 13 percent.)

So, yeah: If you had invested $1,000 in Tesla stock at the beginning of the year, those shares would be worth a total of $8,000 today.

Even though, by most conventional measures, Tesla stock is seriously overpriced. Tesla is trading at a multiple of 170 times forward-looking price-earnings. In simple terms: Based on current profit levels, it will take the company 170 years to make as much money as it's worth.

The average company on the S&P 500 trades at a multiple of 22. So, yeah: That's eight times the average S&P 500 PE multiple. 

Too high?

Opinions are mixed. On December 21, Tesla stock closed at $649. The average analyst price target for Tesla stock is right at $400.

Goldman analyst Mark Delaney recently said the stock price has at least 10 percent more room to grow. On the flip side, in October GLJ Research's Gordon Johnson issued an extremely bearish target of $40, saying, "We think there's elevated risk that fourth-quarter results mark the beginning of the end to Tesla's growth narrative." 

Even Musk, a fellow not lacking in self-confidence, apparently thinks the stock price might be a tad high. In a recent email to employees, Musk said:

When looking at our actual profitability, it is very low at around 1 percent for the past year. Investors are giving us a lot of credit for future profits, but if, at any point, they conclude that's not going to happen, our stock will immediately get crushed like a souffle under a sledgehammer!

So, yeah: Musk realizes that making great cars matters, but making great cars efficiently -- at reasonable profit levels -- matters even more. As Musk also wrote:

... in order to make our cars affordable, we have to get smarter about how we spend money. This a tough Game of Pennies -- requiring thousands of good ideas to improve part cost, a factory process or simply the design, while increasing quality and capabilities.

A great idea would be one that saves $5, but the vast majority are 50 cents here or 20 cents there.

A 50-cent idea doesn't sound like a lot, even for someone whose net worth has increased in the past year from $26 billion to nearly $150 billion. (And even for someone whose initial investment in the company was $6.5 million -- that's "illion" with an "m," not a "b.")

But that's what entrepreneurs do. 

As Netflix co-founder Reed Hastings is widely credited as saying, "Be brutally honest about the short term ... and optimistic and confident about the long term."

Take one small step, and analyze the results. Improve what works. Fix what doesn't. Make smart course corrections. And then take another step.

"You have to look at your own company," Mark Cuban says, "and be brutally honest with yourself and say, 'What do we do well?' That's great. But also be honest and say, 'What do we not do well? Where are our challenges? And then how can we improve them?'"

In short, be confident about tomorrow while, at the same, time taking a cold, hard, clinical view of everything you do today.

That's the entrepreneur's contradiction. Even if you feel you have nothing going for you but a good idea, you have to push past those fears by saying, "I can do this."

And then be completely objective about short-term results to constantly improve your skills, your products or services, and your company.

Because while you may feel you have nothing going for you, as long as you're willing to work hard, persevere, and take a chance on yourself, who you are -- and more important, who you will become -- is more than enough.

Believe in yourself, and you might just look brilliant: To yourself.

Which is the only reflected brilliance that matters.