I'm not really concerned to be honest, as this makes sense. Video production and hosting has some serious costs, and considering they're a private company with no external investors, the money to continue operations and explore new opportunities needs to come from somewhere.
I'm happy enough with the experience I get on Nebula. Compared to the early days where videos would buffer all the time and the highest resolution was mostly 720p, they've come a long way, and it's an extremely reliable platform now.
Not to mention, almost all the creators there edit their videos specifically for Nebula, so no ads/sponsor segments, and some even include additional bonus content that is ommitted from the YouTube release.
The sad thing though is YouTube has conditioned me so much that it feels unuusal for there to be no ads - I'm almost always expecting SponsorBlock to skip an ad segment