Which platform is that? Windows? .NET? It's perfectly possible to target both without using Visual Studio. Microsoft has somehow[0] convinced people that using VS makes their lives easier. Lots of people pay for IntelliJ too. I think the trick here is to get people hooked on languages that have a lot of boilerplate and therefore require a powerful IDE to be usable, then sell people the IDE.

[0]Based on personal conversations with individual VS users, it actually appears that VS is what many developers want or think they want, not just something forced on them by management.

No, I wrote exactly what I meant. As others have pointed out you can use many other free tools, or even free versions of Visual Studio itself.

People pay absurd money (up to $10k per seat) for Team Edition which provides entire enterprise developer/tester/database/architect/team workflow instead of just IDE.

If you build something truly valuable people will pay, so long as they have the money. Like I said, the trick is to find the right people.

Microsoft's compilers are generally free. What you pay for is the IDE. Even those come in free 'Express' editions.