As long as it's not profitable to make money solely off of consulting for free software, but is profitable to sell proprietary software, proprietary software will be inevitable (the company that makes Datomic previously had that business model before deciding to release Datomic as proprietary software).
Both models are/can be profitable, it's down to a personal (strategic) choice from the authors ultimately.
There are many successful stories of proprietary dbs and also a number open sources ones in terms of profitability, ex: Elastic, Datastax, Confluent, Citus etc etc...
Personally I wished it was open-source, it looks quite capable but there is too much risk involved for me to be confortable using it, not to mention it's quite pricey. 1$/day is for dev setups, prod cloud setups start around 4-5k/year last time I read about it, it might be fine for a single deploy backing your service, not when that's a cost you have to add to every client.
Another thing is that it is very specific to some uses and has some limitations (subjectively) that will often require to pair it with other solutions to be actually usable for some things (ex: strings are limited to 4096 characters, no bytes type). All in all it makes sense given what you should use it for (and not use it for), but that's not your usual db product and sometimes I have the feeling that it's advertised as a potential drop-in replacement for <insert favorite relational db> when it's quite often not by itself (arguably, apples vs oranges).
There are also a number interesting of projects that got inspired by it in one way or another, but nothing directly comparable:
* datahike (and the upcoming datopia.io)
* datascript
That said datalog is a pleasure to use and datomic looks fantastic it's just not for everybody.
