I hope you didn't take my comment as saying "don't do it". I am emphasizing that it's a market that seems bigger than it is (at least it does to me).
I found this stat
, only some of them are game developers, let's say half, 25,000.
Now, let's say you get a healthy 5% of that market due to competition, and specialization (i.e. your tool is for 2D games, or the RPG genre, etc.). 5% is 1 in 20 devs using your tool, or 1,250 sales. So, if you sell a product for $100, that's $125,000 in sales.
Now, say you have a team of only two people and that you have zero overhead.
$125,000 / 2 is 62,500/year each. Which isn't a bad salary. It's the 65th percentile of household income in the U.S.
Assuming all that (which I personally think is being optimistic), now you have to sustain that, and get that $100 again each year with up-selling new tools or in version updates.
I'm sure you have plenty of optimism for this endeavor.
I encourage you to work out your own business plan sort of like this and to "count the cost" so to speak.