After 10000 downloads why am I still seeing the attached sales figure

Most of your earnings are probably from those who have unlimited access to Adobe stock. They don't say what you earn for those licences. But it is sure that those plans greatly enhance the sales for contributors. I've read that some people license 3k assets or more per week on such plans.

Actually we do get a 3 cent raise after the first 1,000 sales and another 2 cents after the first 10,000 on the sales from the largest subscription; hiwever those don't  seem to apply to Custom subscriptions - or maybe they do, but since Custom subscriptions aren't a fixed price, there's no way to know.