I imagine there’s some cardboard manufacturing company that was really right place right time when Amazon kicked off.

I dig old computers and used bookstores. Building folio.co and learning about computers at https://show.csprimer.com

Cardboard usage hasn’t especially grown beyond population growth. It just changed from being used in warehouses to being shipped to homes. Amazon uses manufacturers that have been around for 100+ years and grow their own trees, e.g. International Paper, Georgia Pacific, etc