That seems very fair and open to me. You can use it. Self-host it. Modify it, etc. All the benefits of open-source, imo.
It just prevents the only thing I really care about if I'm trying to build an open-source business.
I guess my other question is, why are we -- as a community -- opposed to calling our software "open source" if we use the Elastic license?
The term "Open Source" was created by a group that later became the Open Source Initiative: https://opensource.org/history
By definition, a software license is not "Open Source" unless it meets all the criteria of the Open Source Definition: https://opensource.org/osd
The Elastic license does not meet point six of the Open Source Definition:
"6. No Discrimination Against Fields of Endeavor
The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research."
Therefore the Elastic license is not an Open Source license.
It's your software. License it how you want.
Along with that, it's generally held that licenses with prohibitions like the Elastic License violate some combination of planks 1, 5, or 6 of the OSD.
Now all of this is debatable, and the OSD isn't anything legally binding, but it is widely acknowledge and respected.
This is very much not a case with Elastic. If you build your business on their cloud offering (and use all the latest APIs), it's a great risk. They increase prices? You have to pay more. They go out of business? sucks to be you. The self-hosting alternative would be very disruptive as you'd urgently need to get operational expertise in running and tuning the services, and that's not a simple thing.
So no, Elastic license is not providing major benefits of open source, and thus one should not call it "open source". It's a single-supplier commercial license. Nothing wrong with this, they wrote the code after all, but one should be aware of it when choosing a storage system.