Alastair wrote:

It would be obvious to state that you can't have an observer without a
universe, so why not the other way round? If you can only observe the
universe from the inside, then how can you have a universe without an
observer?

If nobody is around to see you at any given moment, do YOU cease to exist?

The universe doesn't need an observer to exist, either inside or outside.. any
more than you need to consciously decide to make your heart beat from the time
you are born to the time you die.