Termius is free if you just want a nice terminal emulator. You only need to pay if you start using the features that securely sync your connection details between devices, and frankly that's a really useful feature.
That is its one advantage over regular ssh and e.g. JuiceSSH for Android. I can also sync my connection details over dropbox (host+port) and authenticate each device using public keys. Yes, Termius would be a lot more convenient, but the parent's point stands that "is this convenience worth 60$/yr".
I suspect the answer is yes to a big enough portion of sysadmins, especially if they can get their company to pay for the license. The rest of the poor folk get to learn how to build it themselves, as usual.
SFTP, multiple sessions, agent forwarding, pasting passwords, autocomplete
These are pretty basic features that don’t require syncing that are not available on the free version.