Imagine you created your very first app. You developed the concept, workedtirelessly on the key features, design, tested it and fixed the bugs. Themoment has...
Developers deserve to be paid for their time though...
Sure for many it's nothing but a hobby and they're happy to create something for free. But that doesn't mean every developer needs to do the same.
And yes ads are a privacy nightmare and putting them into your app is bad. So either you only use apps from hobbyists or you pay for access (whether that be a set price for a finished product or a subscription for a service).
Developers deserve to be paid for their time though...
If I buy you a free drink at a bar, say "hey do you want this?", and you accept, do I then "deserve" to be able to follow you home afterwards and know where you live?
At the end of the day nobody held a gun to anybody's head and forced them to develop an application, and especially nobody then forced them to give that application away for free.
EDIT: Likewise I don't think developers of such free (as in beer) software owe their users anything beyond the basic expectation that their software isn't malware.
Cryptomator is available on F-Droid but you still have to purchase a license to use it, although the dev has to maintain all the licensing and payment infrastructure which can be a roadblock for some.