It’s a quote that gets attributed to Socrates showing that the issue of one generation complaining about the following generation is a tradition as old as time itself

https://www.goodreads.com/quotes/63219-the-children-now-love-luxury-they-have-bad-manners-contempt

It’s not really sawdust. Cellulose, which is basically plant fiber, is an FDA approved food additive used in things like shredded cheeses as an anti-caking agent. It is commonly extracted from wood pulp, but it could also be extracted from any plant really. Here’s a brief explainer

https://www.npr.org/sections/thesalt/2014/07/10/329767647/from-mcdonalds-to-organic-valley-youre-probably-eating-wood-pulp