According to PirateSoftware (who makes Heartbound), just compiling the game for Max is going to cost you at least $1000 (Mac Mini + XCode license + time)
The number of sales is, however, negligeable - Mac has just 1.38% Steam users
PirateSoftware told [1] that the Mac was 0.02% of their sales - one in 5000 sales (and thus he dropped Mac support)
Don't reinvest in Mac for sales before you do the math.
If you just want a Mac, get a Mac. If you don't want a Mac, don't bother
Thank you for the additional confirmation. We have seen the same stats, which is why we didn't buy a Mac so far. We could build it on GitHub actions, but we wouldn't be able to test it that way. However, depending on the game, the target audience may have a higher percentage of Macs. BlockBawks, our upcoming game, may have a disproportionately higher number of Mac users who are interested in the game because it's dealing with a programming topic. Ultimately, I'm afraid you may just be right and getting a Mac Mini may not be worth it.
I run into this dilemma a lot, not even for profitability.
I would happily test my software on macOS and Safari, but I'm not paying for that privilege. So a lot of my stuff just doesn't work. But Windows, Edge (and previously IE) and Chrome and Linux are all easy to test on so I do even though personally I only use Linux and Firefox.
The number of sales is, however, negligeable - Mac has just 1.38% Steam users
PirateSoftware told [1] that the Mac was 0.02% of their sales - one in 5000 sales (and thus he dropped Mac support)
Don't reinvest in Mac for sales before you do the math.
If you just want a Mac, get a Mac. If you don't want a Mac, don't bother
[1] https://www.youtube.com/shorts/qRQX9fgrI4s