I have never heard anyone complain that slabbing companies hire regular people of the street.

The issue is that the slabbing companies claimed to be offering an "expert" opinion but could not or would tell us the credentials of these so called "experts". If you claim your opinion is worth paying for because you are an expert then you ought to be able to tell us the basis of your expertise.

The question of how you become a chip expert is easily answered, you keep learning about chips. One day I hope to be an expert, but for now I'll just keep reading and talking with the experts and gathering their info.