You almost always have to rewrite your whole system anyway to scale to millions of users. It doesn't matter whether it's PHP, Python, C++, or ASP.NET; it'll have to be rewritten.
The real problem is the flip-side of something that the OP mentioned as an advantage: ASP.NET coders tend to be cheaper, less experienced, and hence less likely to know about some critical detail that'll boost adoption, whether it's usability or latency or security. As someone relatively inexperienced himself, the OP can't know what those things are, but it's highly likely that one of them will bite him.
In other words, it's correlation, not causation. ASP.NET won't make your site suck. However, ASP.NET biases your talent pool towards developers who suck, and that will make your site suck.
I'm curious how you conclude that ASP.NET developers suck ... there's a lot of shit programmers in all languages out there, that's why everyone's looking hard to find the rockstars/ninjas/whatevers.
You're looking for developers who have faced the problems that a typical web startup is likely to have faced as it grows and gains users. It is naturally easier to find those developers if you write it in a language that those current hot web startups frequently use.
To me this sounds like my friends who didn't want to go to UT because it 'was too big'. The awesome thing about too big is that if you look hard enough you are almost assured of finding someone like you.
Yes there are crappy c# developers. I've also seen some bad ass c#.
Right, "biasing your talent pool" doesn't mean that everyone in that talent pool sucks. There are certainly some very talented C#/.NET devs.
The problem is that when you go to hire, you have very little information about just how badass a prospective dev is, unless you've worked with them before. So if you take a random dev out of the C# pool, chances are he'll be worse than a random dev in the Python pool.
So if you take a random dev out of the C# pool, chances are he'll be worse than a random dev in the Python pool.
That was probably true in 1995. But not today. Python has become the new Pascal/Java. Commonly the intro language in CS, so you have a lot of students who graduate using Python regardless of skill.
If you said Haskell, then probably. Actually C++ maybe more then either, surprisingly.
Only if you assume that hits are evenly distributed throughout the day and throughout the month. Very few sites have that sort of traffic pattern. 30 million hits/month quite likely means peaks of 100 QPS followed by periods of 1 QPS.
The real problem is the flip-side of something that the OP mentioned as an advantage: ASP.NET coders tend to be cheaper, less experienced, and hence less likely to know about some critical detail that'll boost adoption, whether it's usability or latency or security. As someone relatively inexperienced himself, the OP can't know what those things are, but it's highly likely that one of them will bite him.
In other words, it's correlation, not causation. ASP.NET won't make your site suck. However, ASP.NET biases your talent pool towards developers who suck, and that will make your site suck.