Elastic.co the n'th most valuable company on Earth and controlled by Earth's n'th most wealthy human being, cloned an open-source project, Lucene, made it easier to operate, and then sold access to it.
You can't pretend that a monopoly plays by the same rules as everyone else. For capitalism to work no one can be allowed to control a market influencing chunk of it.
OTOH, AWS pretty much xeroxed the elastic stack and added a paywall (at least after a year). Compared to that you still get immense value out of the elastic stack for free.
When they decided to implement features that were only available in the proprietary version of ElasticSearch, they open sourced it.
Charging for infrastructure and management of said infrastructure is not the same as placing a paywall on software.