I think the perception (speaking as someone in this group and with a substantial portion of my social circle also within this group - but caveated that outside of professional connections it's mostly gay men and mostly in Manhattan/Brooklyn so definitely not universally representative) is that Biden's stance is more that he doesn't want to promise he won't raise taxes on anyone with incomes in this range, not that he will certainly raise the taxes of everyone in that range. In particular, depending on what and how taxes are changed, it's possible or even likely that some people in the $400,000+ range would still see their taxes go down, and probably we are still more likely to be in the group that sees taxes go down than others (as a still relatively young, high-income but not yet extremely asset-rich group). But also it's a group that mostly wouldn't mind slightly higher taxes as long as the taxes seem to be being put to good use.
I know some Republicans in that range, too, mainly through work (though most people I work with are also Democrats), and they are the sort of who would be upset by taxes increases under Biden, although some of them won't vote for Trump regardless.
Fun sidenote; pretty sure multiple studies have shown gay men couples on average earn more than their straight peers and are disproportionately likely to be wealthy - really interesting consider the group has only recently gained widespread social acceptance.
When it comes to wealth an ideology, it seems like the two extremes are more likely to be conservative than the group as a whole; those who did nothing and came from generational wealth and those who truly had the first gen immigrant came from nothing hustler kind of story, whereas those who got to 400k/year being raised middle class, excelling academically and having a very successful career tend to be more D-leaning.
I think people underestimate how "normal" people making 400k/year + generally are. For the most part, these aren't people living in ostentatious Beverly hill mansions with Bugattis just partying all the time; they're educated proffessionals who are often quite busy and live comfortably but not over the top.
