But some of those top managers have cashed in while exiting or shifting roles within the company, which has a reputation for grueling hours and a passionate CEO, Elon Musk, who pushes employees to the limits.

Tesla’s long hours and big potential pay offs aren’t so unusual for a company born and raised in Silicon Valley’s hardcore work culture. Despite five years as a public company, Tesla still remains nimble and retains its appetite for risk, similar to many of the most disruptive Internet startups.

But Tesla is now moving into a risky and crucial stage of its development, as it pushes to expand with several new products that involve colossal challenges. In some ways it’s acting more like a startup than ever before and likewise pushing its executives to the brink. At the same time, the company will need to retain and recruit key leaders to help it achieve its goals.

When I first interviewed Tesla’s Jerome Guillen over four years ago he was the program director for Tesla’s not-then-released Model S. Following the success of that car, Guillen, an engineer by schooling, was promoted up in the ranks and landed a top job as vice president of worldwide sales and services.

Guillen took over the job after exec George Blankenship left, who at the time stated that he was retiring to spend more time with his family. According to the biography of Tesla CEO by Bloomberg writer Ashley Vance, the relationship between Musk and Blankenship fell apart in late 2012 after Tesla started having trouble converting customer car reservations into purchases.

Fast forward over two years later, and Guillen has had a good run at it. And has also been rewarded.

This year Guillen exercised stock options, and then sold those shares to net over $4 million. On May 11 alone, he exercised options and sold shares for a profit of close to $3 million.

But Guillen’s future with Tesla is unclear. In March, Tesla said it would reorganize its global sales team, and that Guillen would shift to a role that would focus on customer care. At the same time, Tesla emphasized that Guillen was not being demoted and would remain part of the senior executive team reporting to Musk.

Yet according to Tesla’s latest earnings report, Guillen has now taken a leave of absence until the end of the year, and it’s unclear if Guillen will return to the company. Guillen told Tesla he would be taking the leave on August 4, and Tesla’s board subsequently decided Guillen was no longer an officer required to publicly report stock ownership under U.S. securities law.

Tesla’s longtime CFO, Deepak Ahuja, who has publicly said that he’s leaving the company, has also made millions exercising stock options this year. In June, Tesla said that Ahuja, who joined the company seven years ago, would retire but would remain at the company until a replacement is found.

At a recent shareholders meeting, Musk made a point to publicly thank the 52-year-old Ahuja for his work. Ahuja described his tenure as “a nonstop adrenaline rush,” but said he wanted to “check a few things off my bucket list and pursue other life goals.”

The millions he’s made from Tesla will help Ahuja do that. Ahuja has exercised options and sold shares to net over $2 million this year, of which $1 million came this week.

Of all of the key executives, Tesla’s co-founder and long time chief technology officer, JB Straubel, has made the most money this year from exercising stock options, some of which appear to be expiring in the coming months and year. This year, Straubel has netted close to $10 million from his options and stock sales.

But the 39-year-old Straubel doesn’t appear to have any plans to leave Tesla soon. On the contrary, he has seemed to have taken on a more public role, as well as more responsibilities like helping build Tesla’s new grid battery business, which sells batteries to utilities and commercial customers, as well as helping lead the construction of Tesla’s huge battery factory near Reno.

The final months of the year are a crucial time for Tesla. The company has promised to start shipping its Model X SUVs to customers next month. Production will then ramp up dramatically from there, according to Tesla.

It will be a difficult challenge to deliver the new car, and build up production for it alongside that of its current car the Model S. Indeed, Tesla lowered its car shipment guidance for both cars together to 50,000 to 55,000 from a previous goal of 55,000.

But getting the Model X to customers is just the first of the colossal endeavors Tesla has on its to-do list. In addition, the company is building a massive and first-of-its-kind battery factory as part of a push to become a battery maker. The company has also jumped into the grid battery industry, which has itself has only just emerged, and is a yet another entirely new product line for Tesla.

On top of all that, Tesla (TSLA) is hard at work designing the Model 3 car, a lower cost vehicle that it hopes will be able to sell in higher volumes than its previous models. Musk’s goal since Tesla’s founding has been to sell affordable electric cars, and the Model 3 is how he plans to do that.

To achieve all of these huge goals, Tesla needs to both retain its key longtime employees, and find replacements for crucial roles that are now left unfilled. Finding the right executives and keeping them happy will be a difficult job.

Tesla can offer the financial and personal rewards — an exhilarating, mission-driven work environment — that a startup offers. But it’s also got that startup work culture that can lead to burn out.

This startup culture won’t likely go away any time soon. It will probably be the key to Tesla reaching its crazy goals. But it also means that Tesla executives will continue to have to make those difficult choices, weighing the rewards with the upsides.

For more about Tesla, watch this Fortune video: