I should invest time, so that you can sell more? Why?

That's how all platforms work, right? Apple, Microsoft, Android, Playstation, etc.

Yes, but platforms need to make a case for why we should feel inclined to make the effort.

Is the ROI from the potential audience going to be worth it?

Or does it help some people enough that I might want to do it despite no real ROI (i.e. I make the effort to make things not compatible with common assistive tech, even where there is little or no end benefit for me so it is sunk time in that respect, does this new platform quality for my time & attention enough in that way?).

Or is it simply cool enough for me to be interested in playing with it myself?

If none of the above, is there any other reason we should care?

This is especially true if building for the platform means building something new, not just making tweaks to ensure your existing output is compatible.