GT-R is a $1mm supercar that happens to be underpriced at $80k.

Which is what happens when the techniques of lean manufacturing are applied to the supercar design brief. First of this vein was the Honda NSX, I believe.

I have a hunch that the reliability of these cars far exceeds that of the big Italian names...

I belong to a car club that lets you take these out. Supposedly the GT-R eventually disintegrates its own transmission. So did a Ferrari F430. The newer Ferraris don't anymore, supposedly.

IIRC if you use the launch control that explicitly (as in documented in the manual) puts several hundred miles' worth of wear on it - and I'd guess anyone who takes it out in a car club like that will try it at least once (I know I would). Could it just be that?

It depends on the car.

On the 2010 GTR, using it at all voids the launch control. And had automatic ejection from the club, losing your membership. On the 2012 GTR, it doesn't have launch control anymore.

Meanwhile some other cars have launch control which doesn't void the warranty (eg BMW 135i w/ dual clutch. Of course it has half the HP...)

They sold the 2010 at around 50k miles. Similarly a f430's gearbox is only rated for 20k miles.

Do they have Tesla Roadsters?

Wut