Playstation 4, which is the best selling console of this generation, has shipped 57million units, and Sony also makes publishing profits off many of the popular games exclusive to their system. They also have a paid online service. We're talking billions of dollars for Sony alone.
As for why dedicated gaming machines still capture so much of the market as opposed to the "casual/mobile" gaming market:
-Latency would be too high via a Chromecast causing input lag in fast paced games such as shooters (though lower latency, gaming specific streaming services do exist from Sony, Steam, and NVidia)
-Graphical fidelity wouldn't be comparable. Consoles already are the butt end of many "serious gamer" jokes because they don't have the computational horsepower to provide equivalent outputs to high end PCs (Google the "gaming PC masterrace" memes)
-Touchscreens only serve as good inputs for some types of games (strategy and puzzle games come to mind). Racing games, fighting games, RPG's and platformers are usually tailored to controllers.
As I mentioned before, consoles are even mainstream considered to the gaming PC market, which has a ton of dedicated hardware and revenue still despite the desktop as a whole being on the decline (atleast with your average consumer).
Also, you can get bluetooth game controllers for Android.
Switch uses Nvidia Tegra X1 which is a regular tablet CPU/GPU so the switch doesn't have something special under the hood.