It's no different from using an email provider. Just get one that you trust will stay a while. But there are no guarantees. Google could kill off GMail tomorrow.

You'll always have to rely on someone else, unless you build the thing yourself.

The beauty of the fediverse concept is that it's about as easy as possible to build it yourself.

The cost of running a host is a matter of economical management:

• It costs almost nil to run text-based content.
• Images take a bit of memory and bandwidth, but are even manageable with an old cellphone under a set number of users.
• Videos are a major drag, and very expensive unless you're embedding them.

Most open-source is funded as passion projects by devoted geeks who typically already make a living doing other computer things anyway, and fediverse is a bit of the same.

I agree. I think there are moderstion logs though which is a good step towards transparency, I think there should be admin logs too for the same.

As for the running costs, I hope there is a more transparent system rather than running it for profit and selling it to corporations.