It isn't a matter of believe or not.
The speculations about such things are fun to contemplate. They may eventually lead to interesting areas of research.
There isn't enough information to guess at how likely other universes may or may not exist. It sits in the limbo of "interesting" but unknown for now.
This sort of thing is where the long, tentative fingers of the scientific process must probe out. Most of them will encounter deadends. Some will be where the maintstream of science will be in a century.