Is it tacky to buy an ostentatious house that you can only afford because of an inheritance? It may be a little pathetic but it isn’t really tacky per se... also, who gives a &hit what other people think. You only live once. 5-6m in Palo Alto also isn’t ostentatious. It is decidedly upper middle class.
That's not upper middle class. And the OP saying that $350k a year is middle class because he lives in the Bay area is also wrong. Of course the cost of living is higher in these places, but you're comparing income levels in way too small of a sample size. The top 1% of earners in the US make $421k or more. OP's salary almost qualifies him for that, and a $5mil house is living well beyond the means of someone who typically makes $350k (or $421k for that matter). Does it make people feel bad to acknowledge that they are indeed upper class? Neither you nor the OP had to assign what income class any of this stuff falls into, yet you did, and it's so dishonest to try to say that it's somehow middle class.