Most people would consider $60k/year in discretionary income a little more than "decently high".
Although they obviously spend a lot [2], at some point discretionary income gets pretty blurry. I'd hope any reasonable society would consider they have a lot more than $60k at their discretion, though. I make about a third of that, putting me just barely in the top 10%, and have more than $60k at my discretion.
Wealth inequality is pretty insane in this country.
[1] http://money.cnn.com/calculator/pf/income-rank/
[2] https://douggollan.com/2015/05/02/how-do-the-super-rich-spen...
The median salary in the US is $52k.
In light of that, I, too, would call his salary "decently high".
True, true.
It is customary to say you "own" a home you're paying a mortgage on, whether or not you have meaningful equity in it yet.
You can easily find a room in an apartment for less than 1000 $/mo anywhere in the bay. It won't be a nice room if you choose to live in, say SoMa, but it's housing. So you could argue anything over that is "discretionary".
Obviously, many people would consider such a living situation unacceptable. But in the most general sense, it is still a choice.
None of this means that there aren't valid reasons for staying here; even giving up a fairly significant portion of my income as rent leaves me with more money than I'd likely have after rent if I had a comparable job in Tampa, assuming I could even find one. But I don't think this is a sustainable situation for the region. The nanny in the "This is your life in SV" satire, and other people in her salary range (or under it), are on the cusp of being pushed out of the area entirely.