A hard solipsist argument (Revised)

How I came to think of  this argument: I asked myself what, other than my own existence, can I be certain of? Then it occurred to me that, if the world is real then dreams exist and if the world is a dream then dreams exist so, which ever is real, dreams would still be real.

The Argument:

Premise 1: The universe is more likely to be a thing that I know for certain exists.

 

Premise 2: In order for me to say that something exists there must be solid proof or evidence
for its existence.

 

 Premise 3: Unreality is a provable thing. There is solid evidence
that unreality exists. This proof is that "If dreams don't exist they must be a dream of dreams; if illusions don't exist they must be an illusion of illusions thus it is impossible for dreams and illusions not to exist and so they must exist". 

 

Premise 4: Reality  isn't a proveable thing. There is no evidence that
reality is not a dream or illusion.

 

Conclusion - The universe is more likely to be a dream than reality.

 

Objection: But you have to define what you mean by 'exists' and define what you mean by 'thing' and define what you mean by 'universe'.
Reply:   It would be easier if I can start by defining "Dream". Dream is 'a series of images and sensations occurring in my mind' then from that I can say that existence is 'the happening of or my experience of those images and sensations'. A 'thing' is 'what exists or a specific component of what exists'. The Universe is 'the full content of existence or the sum total of all the images and sensations occurring in my mind'.