Disney doesn't release their demographic data. But you can glean a lot of it from other sources.
For example, the Bureau of Labor Statistics has data that shows how much the average American household spends on vacations each year, broken out by quintile. Here's that data from 2017, summarized:
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It's pretty clear that even a day at Disney World for a family of four is going to be beyond the annual budget for the bottom 40% of households. And from Disney's own travel agent media, it's pretty clear they're targeting the top 20%. They're almost certainly targeting the top 10%, 5%, and 1% specifically too.
One interesting thing we got from our (the Unofficial Guide/TouringPlans) surveys is that around 33% of our users' trips involve just adults. That's a higher number than I expected.