Food-delivery platform DoorDash (DASH -0.04%) had a surprisingly good year in 2021 despite economic reopening. Some investors were concerned that the company would not do so well when restaurants opened again and folks had the option of dining indoors.

With the new year upon us, let's look at DoorDash's business and determine whether investors should buy, sell, or hold its stock.

A person making a delivery to a customer.

Customers can get food delivered to their homes for as little as a few dollars with DoorDash. Image source: Getty Images.

DoorDash offers an excellent customer value proposition

Interestingly, in the nine months ended Sept. 30, DoorDash's revenue increased to $3.6 billion. That's up by 89% from the $1.9 billion it reported during the same time in 2020. The growth is impressive, considering restaurants reopened and welcomed guests for in-person dining.

DoorDash thrived at the pandemic's onset when folks could not dine inside restaurants. It was a twofold benefit to the food-delivery company. First, without the option to dine inside their favorite restaurants, people ordered for delivery instead. Second, with their in-person business halted, restaurants became more interested in partnering with DoorDash.

The company built on that momentum and added partnerships with merchants in new categories. In addition to restaurants, DoorDash now delivers items from grocers, convenience stores, flower shops, and more.

Consumers are voting strongly in favor of the convenience DoorDash offers. For a few dollars per order, folks can avoid the necessity to drive or walk to the nearest restaurant or grocery store. For some people who lack transportation, DoorDash is an even greater value.

The customer value is obvious and has helped DoorDash supercharge its revenue growth from $291 million in 2018 to $2.9 billion in 2020. It's on pace for even more in 2021.

The difficulty has been for DoorDash to offer this great value to customers sustainably, in a manner that generates reasonable profits for the company. In the nine months ended Sept. 30, DoorDash reported $313 million in losses on the bottom line, more than double the $149 million in losses during the same time in 2020.

A massive addressable market at a favorable price

That concern for profitability might be one reason DoorDash is selling at the lowest price-to-sales ratio in its brief history as a public company. Its P/S ratio of around 10 is less than half the 25 it carried at its peak.

Fortunately for shareholders, DoorDash is generating healthy cash from operations -- $525 million in the nine months ended Sept. 30. What's more, DoorDash is addressing a massive opportunity. The estimated total local retail market is valued at $4.1 trillion annually in the U.S.

The relatively inexpensive valuation, positive cash flow from operations, and massive market opportunity are all favorable to DoorDash as an investment. However, the big question remains whether it can operate the business profitably. Therefore, investors considering DoorDash for 2022 can be cautiously optimistic.

To more precisely answer the question in the headline, in my opinion, DoorDash stock is one to hold.