That is the issue. It is not that it isn't worth $250 for the Pro version if you use it everyday, but it isn't worth it if you only use it twice a year.
I don't really know Omni or their products, but I wonder from reading some comments here that while the bottom end of their market has been eaten by cheaper/free alternatives, the pro market that will happily pay $250 for a great tool has been eaten by things like Figma with the online collaboration that has become essential for professionals.