It's mostly a toy for hobbyists.
While HTML5's platform compatibility gives you the ability to export to any platform, it never really excels at any of the platforms it works on.
It's a jack of all trades, master of none.
While you can make Android/iOS games from the same HTML5 project, both their performance and functionality are very limited. You have to work with really large limitations, both performance-wise and in terms of what you can implement in your games.
You can export a project to PC as an .exe file, but you have very little control of the file system, and you're never running "native" - it works through a bare-boned version of Chrome called Chromium. While it's compatible with any PC out there, Chrome/Chromium tends to give different results on different PCs. For example, after applying a coloring-effect, a cloud appears Green on my PC and Red on friend's.
WiiU is something that is in the works of being implemented, but really, who has a WiiU anyway?
Ouya - Look at android section.
PS and XBOX have we no news or info about.
All that said, it's still a hobbyist tool. I don't think i've heard of anyone earning more than a few hundred bucks a month with Construct 2 Games/Apps. And there's less than a handful of people doing that.
If you have amazing ideas, and are ready to work around the software's limitations, sure you can make anything and earn millions with it. A game's profitability has rarely anything to do with the way it's made. It's all about a great idea with great gameplay and the limits of your own imagination and dedication to it!