If we're playing tennis, it's pretty freaking easy for me to win if you keep serving the ball out of bounds or into the net. 

Nintendo repeatedly shoots themselves in the foot, competing against them in the console space is easy. 

They have completely different audiences. It's like they're playing on different courts.

Sony's strategy is really smart ... just wait for the other guys to screw up and release a competent console in the meantime.

Aside from the PS3, where they had to push the Blu-Ray format ... they've largely stuck to this philosphy.

Nintendo will always fold like a house of cards, they can't help making stupid console decisions. Sega was the same but more of a gong show financially.

Microsoft is a tougher match up for Sony directly, but they made the grave error of taking this generation too lightly IMO and thinking they could just show up and dictate to consumers based on brand strength. And when you start thinking like that, you get yourself in trouble.

Always a mix, but I do think out of the gate Microsoft's stumbles have aided them as a competent $399 competitor would have made things much closer, at least in NA.

Would you say the same if Sony's mistakes factored more into the xbox 360's success rather than it's merits ? 

It's a fair mixture of the two. PS4 couldn't be what it is without both Sony doing so right and MS/Ndo doing so wrong.

Microsoft lost confidence from a lot 360's buyers a long ago, it wasn't just because of the DRM. On the other hand, Sony fixed all the problems that PS3 had on its launch, so the console was destined to success sooner or later. And Nintendo failure doesn't affect to Sony or Microsoft at all if you ask me.

Nintendo doesn't have an audience this generation other than "Nintendo lifers", which is a small demographic overall. The kids and especially the casual markets have both ditched them. 

Nintendo's kind of cornered themselves into being irrelevant in the console space ... which I'm sure suits Sony just fine aside from their concern that a weakened Nintendo doesn't bring in as many kids nowadays (future Sony customers) because they're going crazy over tablets/phone games. 

IMO, they ditched the casual gamers with the release of the gamepad.  I mean, I think it's kind of cool in some ways but I am not a casual gamer.

I think it's a little of both. To Sony's credit, by making the PS4 a more powerful system, with no added peripherals like the camera packed in, thus reducing the price to a much more consumer friendly level, and by producing AAA games with the PS3 even towards the launch of next-gen systems, made the fans go: