I've no strong opinion on which is the most useful way to look at things (MWI, CI, or maybe a form of non-local hidden variables), and this post is not to refute anyone here, but I've a few comments/questions:
1. 'I think, therefore I am', is the only deductive proof, and therefore the only 100% proven thing. All other things are "proven" inductively and therefore not quite 100% proven. So solipsism (unfortunately) can't be discounted. However, IMO its extremely improbable. I think we're agreed on this.
2. I think one reason some embrace MW is that we are trying to make QM events consistent with classical probability theory so that we can "understand" QM events. But note that we learned classical probability theory by studying strictly classical phenomena. (like creating axioms to describe a swarm of bees and then trying to apply those axioms to a single bee)
3. Isn't CI just "shut up and calculate" and the word "superposition" without a rigorous definition? (This is an honest question). If so, then embracing that view will never allow us to answer the important philosophical question (IMO), "Is there true randomness (pure chaos) in the universe, or is there only pseudo-randomness and no chaos?". Frankly I've vacillated between the two over the years. My latest guess is that the simplest reality is one in which all events are possible (chaos)--but then perhaps only non-paradoxical events were able to evolve to higher order, like conservation of number, etc. So maybe the randomness we see in low-energy events is a glimpse of that chaos.