Big tech didn't steal anything. Elastic used open source software as the foundation of their product (specifically, Apache Lucene), and released their product as open source. The license allowed Elastic to do so, and likewise, the license Elastic used allowed "big tech" to use Elastics product. If it wasn't for open source, Elastic wouldn't exist.

Then, Elastic whined about Amazon using Elastic under the open source license they used to build their product. They whined that Amazon wasn't contributing enough. So they switched the license to their product. So Amazon took over maintaining the open source software. Doing exactly what Elastic asked them to do.

Sorry, but everything about Elastic, and especially this most recent announcement of layoffs, scream "bad leadership".