Hold on... A ton of broadcasters, production companies, and individuals have done it and are doing it.
YouTube have many competitors and some of them are enormous, such as Netflix and cable TV. Production companies are popping up all the time and are making some of the world's highest quality material. The same for individuals who are making videos.
Or do you mean that YouTube needs a competitor that does exactly the same thing as YouTube?
All of them are based on the traditional media production model. The companies were all well established in the industry (minus Netflix) and the only change was to go from broadcast/cable/theater to streaming. YouTube pioneered user generated videos and independent content creators. Its only competitor is probably Twitch, but that itself is owned by Amazon and losing a ton of money.
No one does video even remotely close to the scale YT does it. YT has by far the deepest market penetration (close to 3 billion monthly users), and has by far the most hosted content, and critically, youtube adds over a half-million hours of video a day.
Essentially, youtube adds more video every single day than the entirety of every other streaming service offers combined.
Youtube is in it's own category, and it's unsurprising no else wants to touch it.
Serving user generated content is very expensive in terms of infrastructure. More expensive in many ways than streaming studio generated content.
The scales of the two models are very different. Ingesting content is more complicated with user generated content because there's few guarantees about formats (encoding, color, file formats). Serving the content is also more complicated because it's not as friendly to edge caches as studio content. Part of the expense of YouTube is the long tail of content. Popular content might live in edge caches but YouTube serves up old unpopular stuff too.
Those things do not sound like a very big hurdle for a massive company like Netflix, in my opinion. They could simply demand a certain encoding, color and file format from uploaders. As for edge caching, not my specialty, but if Google can do it so could probably Netflix.
The most difficult part, and one that Youtube has struggled with since the beginning, would be content moderation. It's a technical, legal, and PR nightmare and there's no reason for Netflix to wade into that mess.
Then why is there reason for YouTube to be in that mess? Netflix currently has no problem in broadcasting and selling some of the vilest and most offensive stuff imaginable, including outright child pornography.
YouTube have many competitors and some of them are enormous, such as Netflix and cable TV. Production companies are popping up all the time and are making some of the world's highest quality material. The same for individuals who are making videos.
Or do you mean that YouTube needs a competitor that does exactly the same thing as YouTube?