As others have said, the best solution here is to run a private relay. This allows you to backup your notes and events, but also puts you in control of your data. At some point in the future, you'd be able to broadcast your notes and events to other relays so that your followers can view your content. It's anti-rug technology.
Discussion
Is there a preferred relay people are running? I see there are quite a few implementations.
Wouldn't it make sense for relays to charge extra for long term storage?
Yes, but a relay can always rug you. If you backup your own data, you're in charge.
That's the same trust model as for everything else. The payments could be tiered or even usage dependent, and one can always use multiple relays to have redundancy. But sure - if you run your own relay, even better for you.