The two most profitable companies I worked for used PHP. And nowhere close to the newest versions. The two least profitable both used C++.

Even with those experiences I would never say there's a correlation between chosen language and success, because in all those cases it was the core business idea that was the driver of success or failure.

I do still try to choose the right tool for the job based on some kind of instinct and experience anyway.

Also, congrats on your gig. From where I'm standing (an old fart still grinding it out at startup #7) that sounds totally awesome. This is going to be my last startup though, I was going to accept my fate and go work for some BigCo before it's too late otherwise I'll have no retirement at all. But if I could find a nice niche like that, I'd happily work part time forever.