Plenty people spending a lot of their time working on Postgres have complained about Amazon's style of using open source. Among them myself (long before working for an AWS competitor). Most of us don't have problems, or even the opposite, with companies making loads of money with Postgres. What I/we am severely disappointed with is that they barely put resources towards contributing back. Every now they make grand statements about their community support, but in the end little materializes.

This is purely my personal opinion.