The only reason youtube still exists with no viable alternative (for the populace) is the sheer amount of content thats uploaded on the platform and creators already being there as well as the difficulty/cost of sustaining a service that stores and serves video. There are so many platforms that do youtube’s job as well if not much better than it but that will never rival it because youtube simply has all the content and content creators.

EDIT: imo odysee and peertube are the best alternatives we currently have but they will sadly never make youtube fear a single bit for their market share