I used to think exactly the same way but a few things changed the way I looked at things:

First of all I learnt to lighten up a little (no offence intended)

I also had a few uncomfortable moments that betrayed my then belief and more importantly - assumptions.

Not always but a few times I have heard differences that I cant explain. In most occasions it's been a bummer for me as its often been new equipment that I wanted to keep but I didn't like the result.

This is not just amps or speakers, I once bought a remote control mains socket fo the hifi. This was great as I could just switch the whole thing on from anywhere in the room, I had everything to gain. However there was something different with the sound, I noticed that I was find the treble quite course an dthe bass a little shy. I left things as they were for a while but just couldn't live with it. I took the adapter out and I had my old system back. Madness I thought, I must be a loony. A month later I put it back in thinking I that I imagined it but the same thing happened!!

There is a lot of shit out being sold by unscruplus people but dont assume that everyone is telling porky pies.