Hey Dmitry,
I personally do not 🙂 I only want you to buy what you think is necessary for your site. If you check out the full page for the Filter Bar add-on which I linked to above, and read through all the features and look at the screenshots, it does a lot more than just add one filter.
You can get extremely granular with your filtering, and even filter events by locations and distance if you have the PRO calendar add-on. And you can specify almost everything you want about the filtering behavior itself – this is shown, for example, in this screenshot → https://theeventscalendar.com/product/wordpress-events-filterbar/
If you don’t need this functionality, no need to buy it. If you just need some simple filtering, and not all the features in this add-on, then you can write some custom code to enable some more simple filtering on your own or hire a developer and not have to get this whole add-on.
Let me know if this information helps here, or if you have any other questions, comments, or concerns.
Cheers,
George