OSS doesn't have anything to do with business models. Anyone can create open-source software and many do. The whole point is that it's free to create, see and modify. Some companies choose business models which include open-source software, and that comes with advantages (increased popularity and growth) and disadvantages (free usage, forks of codebase).
The reality though is that tech has changed and customers don't want to buy software, they want services now. ES has been slow to offer this, and they still offer it poorly, which is why AWS and other companies have filled in the gap. This is how business competition works.
Please answer these questions: Do you have a problem with the other companies (which are smaller than Elastic) that offer managed elasticsearch? Do you have a problem with multiple companies offering hosted Wordpress? Do you have a problem with any company that sells software or services that use open-source components?