Yes indeed they do and you are right. I just think that of all the fields in science, theoretical physics is the
least 'scientific' - it is philosphy and making up wonderful stories supported by mathematics for it's own sake.
They build upon uproven theories and act like it is fact.
I can't think of any other field where you can get an unproven theory, link it to another unproven theory using maths, and be mega famous.

You can't postulate M-Theory until all the sub sets of string theory are proven and then you come up with the overarching theory to embrace the rest.
It is kinda like if they built a computer in 1600, hoping that electrons exist. No, prove the little bits first.
They may be right..... but I hope they discover a new particle that totally writes off string theory and they discover the Brane theory (or some other) camp were right.