As a developer you should NOT have to pay Apple or Google or anyone any money to create / distribute software. Developers create real value to a platform, and no self-respecting developer should encourage this kind of exploitation. App Stores also exploit customers and also violate their privacy.
Note that the usage of App Stores on a Mac is not at the same level as that of iDevices (where everyone is forced to use the Apple App Store to install any software). And many Mac developers also sell / distribute their products outside it. Since your application is a Mac app, you do have a real choice to avoid App Store and distribute your app online through other means.
All that said, it's pretty hard to judge how much the App Store can help you sell your product because it depends on various factors like how useful your product is to your target market, how well-designed your product is, who your competitions are etc. Whether you can make money also depends on your business skills.
1.5% + €0.25 for standard European Economic area cards
2.5% + €0.25 for Uk cards
So, how is that “you should NOT have to pay […] anyone any money”?
I also think that’s just for the selling part. Distribution, you’ll still have to do yourself. Apple and Google handle both, plus automatic updates for your customers, for you.
(Also, for a low-selling product and a €0.99 price point, the cost of Stripe is about par with Apple’s flat 15% plus €99 per year)
If you keep aside the hyperbole, you should have understood that I am talking about fighting against anticompetitive behaviour devised for exploitation by corporates. There is indeed a difference in paying 5% to stripe for their services vs being forced to pay 15-30% to Apple just because they have placed artificial technical barriers to prevent you from turning to their competitors (in some particular segment of business).
Note that the usage of App Stores on a Mac is not at the same level as that of iDevices (where everyone is forced to use the Apple App Store to install any software). And many Mac developers also sell / distribute their products outside it. Since your application is a Mac app, you do have a real choice to avoid App Store and distribute your app online through other means.
All that said, it's pretty hard to judge how much the App Store can help you sell your product because it depends on various factors like how useful your product is to your target market, how well-designed your product is, who your competitions are etc. Whether you can make money also depends on your business skills.
My advise - just sell and distribute the app yourself ( https://stripe.com/resources/more/how-to-start-a-digital-pro... ) and use the $99 on Google Adwords to promote your app ( https://business.google.com/in/google-ads/ ). How many people searching for the feature that your product offers, click your ad and buy your product will give you a very fair idea of the commercial viability of your app.