Tesla’s reversal of fortune is a jolt for both the company and its chief executive, who had built a reputation not only as a visionary but also as an achiever, masterminding an automotive brand, breaking ground on a battery plant that would be the world’s biggest building, and launching rockets through his SpaceX venture.

For years, Tesla has ridden a wave of enthusiastic support from its customers and a certain set of investors, even though it generated barely any profit in the 15 years since its founding. Company events to present new models tend to have the feel of a religious revival, with hundreds or thousands of owners cheering wildly at each new pronouncement from Mr. Musk. Anticipation for the Model 3 prompted nearly 400,000 prospective customers to put down deposits of $1,000 each.

In November, before a screaming audience of several hundred guests, Mr. Musk unveiled a battery-powered semi truck and a two-seat roadster. He vowed to begin producing the truck by the end of 2019, even though the company does not have a factory to build it, and is still trying to work the kinks out of the Model 3 assembly process at its manufacturing plant in Fremont, Calif.

“There is a huge part of Tesla that is simply presentation and not substance, and Elon is a master at messaging,” said Karl Brauer, a senior analyst at Kelley Blue Book. “The problem is the reality is starting to stack up, and that’s a reality of accidents the cars have had, quality issues, and massive misses on Model 3 production numbers. You add all that up and there’s a real question about whether this company can deliver what it promises.”

There’s no doubt Tesla has achieved some breakthroughs that have left the established automakers scrambling to catch up. It has proved that there is a viable market for electric cars, and that they can command premium prices. It has pioneered methods of upgrading cars through software updates beamed over the air, the way iPhones can download new operating systems.

And it was Autopilot that set off a race to develop advanced driver-assistance systems that can guide cars under certain circumstances and actively prevent collisions — though Tesla’s technology appears to have been surpassed by the self-driving systems from other companies, including G.M. and the Google spinoff Waymo.

Along the way, Mr. Musk has also courted controversy, including his move in 2016 for Tesla to take over SolarCity, a maker of home solar panels run by his cousin. A group of investors has filed a lawsuit contending that Mr. Musk had a conflict of interest because he was SolarCity’s chairman, and this week a judge cleared the way for the case to go forward.