My point was more on the sponsorship rather than the transition. Even if you manage to move 20% of the audience, the sponsorship amount would be less than 20%. Most companies play it safe and allocate budget for proven marketing platforms and wouldn’t be willing to put much on a new platform. So while it takes someone to switch platform and convince their audience, there wouldn’t be adsense money or sponsorships with no guarantee they would even make 10% of what they used to make on YouTube. Most youtubers are after the money and if anyone is doing it as full time job, that would be an unreasonable request.

All of those venues wont be reaching out to you if you are not on YouTube or have enough reach on a different platform. I do hope content creators post on multiple platform but it is not reasonable to think that they can just flip a switch and start posting outside of YouTube.