The idea of 'thetans' being the spiritual controlling force of this universe is hilarious and the fabrication of believability is even funnier yet.
The term 'thetan' has evolved quite a bit from it's sky-high beginnings. Hubbard, as he progress through his created subject matter, continuously tweaked the 'thetan' concept. He still didn't get it quite right, mainly because he refused to get over the fixed idea of 'thetans in control'.
From thetans being a 'static' to controlling bodies, these versatile little valences, yes, I am calling them valences, were everywhere, doing everything. The notion of understanding these valences brought about the idea that 'power' could be gleaned and used against other 'thetans'. It's just not workable.
Trying to understand a valence is pretty silly, especially when one is on a 'power quest'. Think about it for a while. Does it make sense to become something other than what you are? The intellectuals will demand answers as proof of believability, but questions and answers hide truth. You can't know truth when you are seeking it.
Declaring that a 'thetan' is a valence can be a shocking statement. Take a look at how you view a 'thetan' and see how it becomes secondary to what lies beyond it. Want to move mountains? Looking for lots of cash? Do you want to be idolized by loads of people?