A bunch of tech companies are suddenly having parties with a theme of 1920s-style excess

There must have been a run on flapper dresses and fedoras in Silicon Valley this holiday season. 

At least four of the major tech companies in the Bay Area all had the same theme for their holiday party: the "Roaring 2os." 

That period of high-flying excess and the idle rich was memorialized in F. Scott Fitzgerald's "The Great Gatsby," and it seems to be the inspiration for this year's holiday season. 

Most of these parties featured the same sparkly extravagance that marked that time period right before the Great Depression. 

Facebook's holiday party featured high-flying dancers, a casino room, and golden palm trees.

Pinterest and Google's marketing team rented the same space to throw the same party.

Google's marketing party even hired a specific Gatsby event group (it's that much of a thing now). 

Pinterest also played up the speakeasy theme with the alcohol clearly flowing.

Even Yahoo was in on the game, reportedly spending $7 million on its Gatsby-themed party on Pier 48 in San Francisco. 

There's some irony in the popularity of this theme this year.

The 1920s were the previous peak of income inequality in the United States, as measured by the percentage of income earned by the top 0.1% of earners. That peak has been passed in the current post-recession era, according to a 2013 study conducted by UC Berkeley:

And in the San Francisco Bay Area, at least, a lot of people blame tech companies and their employees for driving up real estate prices and rent, which is driving poorer people out of the city. 

The Roaring 20s ended with the market crash of 1929, leading to the Great Depression.

It's obviously not a sign of a terrible things to come at all these companies, but some analysts are making the argument that lavish excess should not be spent by companies (read: Yahoo) that are in financial trouble.