Saw this comment about someone making around $1500 per month with an online solitaire game: <a href="https://news.ycombinator.com/item?id=23666935" rel="nofollow">https://news.ycombinator.com/item?id=23666935</a>
Not a developer but I guess most HTML5 game developers are focusing on itch.io etc platforms for money. Apparently, Html5 game can't compete with native games on your mobile phones and should be only count for a very tiny part of ecosystem.