Beyond the issues of infrastructure cost and litigious publishers as mentioned by others, there is also the user base.
If users are on YT, that is where the content creators will be. And if the content creators are on YT, that is where the users are. Moreover, users have curated lists of subscriptions and creators have large lists of material. Finally, YT has access to a lot of data on viewing behavior, and likes. This means YT should be a lot better at recommending videos to users.
Finally, the creators that most want to switch to an alternative are those who are the most censored. These tend to be more controversial, which means these alternative services gather controversial content. This tends to give these places a bad reputation which pushes away the non-controversial content.
The best bet would probably to take a non-controversial niche, start there, and try and integrate well with YT to keep down switching costs. Its still hard to provide actual added value to such a niche. Alternatively one might take a controversial niche with wide acceptance. For example, gun channels or LGBTQ+ channels. Both are currently demonetized, but both are still widely accepted in broad swathes of society.
> YT should be a lot better at recommending videos to users.
this is hardly the case, as any avid youtube watcher can tell you. Recently, the algorithmic suggestions are terrible, and either show repeated content, or content that's not even close to what's being watched (but the SEO/words in the description/title matches), or is a huge list of videos from the same channel.
If users are on YT, that is where the content creators will be. And if the content creators are on YT, that is where the users are. Moreover, users have curated lists of subscriptions and creators have large lists of material. Finally, YT has access to a lot of data on viewing behavior, and likes. This means YT should be a lot better at recommending videos to users.
Finally, the creators that most want to switch to an alternative are those who are the most censored. These tend to be more controversial, which means these alternative services gather controversial content. This tends to give these places a bad reputation which pushes away the non-controversial content.
The best bet would probably to take a non-controversial niche, start there, and try and integrate well with YT to keep down switching costs. Its still hard to provide actual added value to such a niche. Alternatively one might take a controversial niche with wide acceptance. For example, gun channels or LGBTQ+ channels. Both are currently demonetized, but both are still widely accepted in broad swathes of society.