Because for historic reasons, Youtube has a monopoly position on viewers and the content creators need those viewers, despite that they have to resort to other

Because for historic reasons, Youtube has a monopoly position on viewers and the content creators need those viewers, despite that they have to resort to other means, like Patreon, merchandise or product placements/sponsorship to make any money themselves. This won't be the case forever, I hear more and more people (creators and viewers alike) complaining about Youtube, its monetisation and it recommendation algorithms.