It's no surprise to me that this is happening on Capitol Hill. http://www.glbtq.com/social-sciences/gentrification.html has a good explanation that I think applies to Capitol Hill. In summary, what tends to happen is that a neighborhood first transforms into a gay center, which happened for Capitol Hill in the 70's/80's. Later, these neighborhoods become trend centers, which drives a second wave of gentrification, happening now on Capitol Hill.

While glbtq people in general are participants in gentrification, gay men in particular are often at the vanguard of gentrifying neighborhoods. This is because they tend to have a higher percentage of disposable income and often want to live in urban centers that are tolerant and culturally vibrant.

Many of the neighborhoods that gay men move into and gentrify were previously working-class or poor neighborhoods primarily populated by black residents. These areas often have historic homes that the new residents restore while complaining that the old residents have done little to maintain their own. Examples of locations in the United States that have experienced this sort of gentrification in recent years are Asbury Park, New Jersey; German Village and Clintonville, in Columbus, Ohio; Dupont Circle, in Washington, D. C.; Lakeview (known colloquially as Boys Town), in Chicago; and the Oak Lawns/Cedar Springs area of Dallas.

Once gay communities are established in gentrified neighborhoods, however, there is a significant chance of a further wave of gentrification that transforms the neighborhoods from gay centers to high-cost trend centers. As this happens, low-to-middle income gay men, as well as lesbians (who tend to have lower incomes than gay men, as women in general have lower average incomes than men), are priced out of the neighborhood. New wealthy heterosexual residents then replace gay bookstores with high-end boutiques, gay performance spaces with mainstream movie theaters, and political action centers with entrepreneurial startups.

Emphasis mine. There's a lot of academic research on this topic (see https://scholar.google.com/scholar?q=homosexual+and+gentrification). It's not just Capitol Hill where this is happening. The same thing happens in many gay neighborhoods around the world. Cities that aren't tech centers and don't have Amazon.