Why does YouTube have no competition?

The hosting costs would be astronomical for a startup to offer free HD video hosting in the modern era. Google had deep pockets to buy them and pay for servers for all of the years YouTube was not profitable. A viral video like Gangnam style which currently has 3.6B views probably cost in the millions to serve. Luckily Google has the ad muscle to recoup that, but not many others could. If someone were applying to YC or approaching VCs with a YouTube competitor, the big questions that I'm sure would come up are, "what have you figured out that YouTube hasn't that will make users flock to you" and the obvious followup if you have a clever answer to that: "why couldn't Google beat you by just doing that first or better?"

EDIT: thinking about it further, the company most suited to offer it would be Amazon, which obviously has the storage space and hosting infrastructure, but not the advertising network to make revenue on it. It would be interesting if they could tie into Prime Video to allow users to monetize their content via a revenue split with Amazon.

They seem to do discovery very well, as in finding creators an audience. And, they actually pay content creators. That's let them build a lot of inertia. You'd have to steal away both the viewer base and the creators, and that's not trivial. Twitch and tiktok are competing by creating new categories to compete in, but in terms of just upload a video and go viral land, even Facebook hasn't been able to really replicate the value YouTube provides.

I wouldn't say that they have no competition, just that they control a high majority of their market and are much larger than their competitors.

Vimeo and Dailymotion are YouTube's largest mainstream competitors. PeerTube and D.tube are also two decentralized alternatives.

It does, at least in other countries, e.g. in China there is bilibili.