Media-streaming technology specialist Roku (NASDAQ:ROKU) had been on my radar since it produced the first set-top box that could stream Netflix (NASDAQ:NFLX) content in 2008. The company entered the public stock market nearly 10 years after that. It still looked like a great idea in 2017. Global interest in video-streaming services exploded last year, but I never got around to pulling the trigger on buying Roku stock.

That changed in 2020 when the COVID-19 pandemic turned the entertainment industry inside out. Roku's share prices fell for some ridiculous reason, and I finally picked up a few shares near the absolute market bottom in March 2020, in two separate transactions.

Almost exactly nine months later, my Roku holdings have posted a total return of 283%. You won't find me cashing in those winnings anytime soon, by the way. I expect Roku to be a cornerstone of my long-term investment portfolio for years to come, right next to my older and larger holdings in Netflix, Amazon (NASDAQ:AMZN), Alphabet (NASDAQ:GOOG) (NASDAQ:GOOGL), and Tesla (NASDAQ:TSLA).

ROKU Chart

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Better than the best

Roku isn't my most successful investment in 2020, by the way. That trophy belongs to digital ad-buying expert The Trade Desk (NASDAQ:TTD), which I also picked up in March with a handsome 439% return so far. I am far less committed to holding The Trade Desk in the long run, though. That purchase was more of a bet on a strong rebound from a dramatically undervalued stock price, and that story has been told. I'm in no rush to sell my Trade Desk shares, but this stock has already justified my original investment thesis. I'll review the company and its stock from time to time, perhaps resulting in an early sale if the conditions are right.

Roku is different. I believe we're looking at the future of home entertainment here, poised to benefit from the market-expanding investments that are being made by content-streaming providers such as Netflix and major movie studios. The entire media sector has turned its eyes to the global and long-lived growth opportunity of a strong video-streaming market. Roku is a near-guaranteed winner, no matter which video services turn out to be winners in the long run.

The company is also improving its business model by paying less attention to low-margin hardware sales. Software licensing sales accounted for 70% of Roku's third-quarter revenues, roughly in line with management's product-mix target for the long term.

A hand holds a pair of scissors in position to cut a cable-TV coaxial cable.

Image source: Getty Images.

This is still an elite investment idea

That's why Tesla is my best buy in 2020. Sure, The Trade Desk has made me a bit more money thus far, but I expect Roku's returns will stay strong for several decades ahead. I own nearly 30 different stocks these days, but only the small handful I mentioned earlier belongs to that exclusive club of portfolio anchors for the long run.

Roku joined this elite club in the spring of 2020. Make yourselves comfortable, folks. I expect you to stick around for quite a while. Don't be surprised if I add a few more shares along the way, because Roku is still a fantastic buy today.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.