Earlier quoted context omitted.
Everything that doesn't serve a human basic need, of which there are many. Food is not worthless in itself, nor is shelter, security, human contact, etc. Extreme subjectivism never fed nobody nor kept them worm. It only made them think they are smart.
You don't understand what in itself means, it is a philosophical term used to distinguish between being in itself of something versus being of that for someone. For example there is no food in itself, food is always food for an animal in itself its just some matter. In the same way there is no value inherent in anything as it is in itself, but becomes valued by humans on the basis of speculation, use and rarity.
Solipsism 2.0