I seriously doubt IE6 support can be the difference between "wildly profitable and failing" for any business. Can you name one example of a failing company that started supporting IE6 and then became wildly profitable?
And, yes, I can give a few examples were the webdevs ignored legacy browser support and got burned.
But just last week, another subcontractor apparently didn't realize that our government client was stuck on Flash v9 and spent the next two weeks trying to sort it out.
And it hasn't happened in a few months, but we used to get occasional complaints from clients stuck on Safari v4.