Okay, let's look at things a different way:
At $300K, you pay around 40-48% taxes. You take home roughly $180K or $15K per month after taxes.
According to the Census Bureau:
In MD, the median HHI is $74,551, 80th percentile is $140K,
In VA, the median HHI is $65,015, 80th percentile is $128K
In DC, the median HHI is $70,848, $148.8K
You already take home about 250% of median income pre-tax. You take home 130% of the bottom 80 percent of households make pre-tax.
Middle class is typically the middle 50% of the working population, roughly from 25th to 75th percentiles. You take home significantly more than these people even earn.
It doesn't matter how you spend your money, but your income makes you "rich". Just because you spend it, doesn't make you poor. Middle class is about making compromises and setting priorities to get the most important things and compromising on the less important. You have the luxury of being rich, of being able to fully fund retirement, buy a home with a shorter commute, in a good school district, buying newer cars, going on vacations, paying for daycare, for private school, for expensive summer camps/programs.
Middle class people cannot afford to make the choices you make. Owning property in good school districts of NW, Montgomery County, and pricier parts of NoVa is just not an option for the middle class. Being able to fully fund housing, retirement, college funds and still pay daycare and have leftover disposable income is not an option for the middle class.
The problem is that the middle class is not what it used to be. Too many people are trying to define middle class as "what my parents had when I was growing up". There are people who live in MoCo that grew up there that thing that on their $250K or $300K income, they should be able to afford what their parents did when the PPs were growing up. That's not the definition of middle class. The problem is that the population of the region has nearly doubled in the last 30 years. The influx of over 3M residents into the region means that the more desirable housing becomes much more expensive as demand increases. We have not doubled the avialable housing in the more desirable areas, so that means that the same income will not be able to buy into the same parts of town. So it means that areas that used to be middle class are no longer middle class. It doesn't mean that those who earn that amount are no longer middle class, only that middle class can not afford the same parts of town that their parents afford.
You are in the top 2% of the household income in the region. You make more money that 98% of the households in the region. You are rich.
References:
https://factfinder.census.gov/faces/nav/jsf/pages/community_facts.xhtml?src=bkmk
http://statisticalatlas.com/state/Maryland/Household-Income
http://statisticalatlas.com/state/Virginia/Household-Income
http://statisticalatlas.com/state/District-of-Columbia/Household-Income