One factor might be the increase in binge drinking during the pandemic, which I suspect fuels at least a certain fraction of anger and bitterness, along with the post-alcohol depression effect, in conjunction with economic and related stresses:

> "Using data from a national survey of U.S. adults on their drinking habits that found that excessive drinking (such as binge drinking) increased by 21 percent during the COVID-19 pandemic..."

https://news.harvard.edu/gazette/story/2022/01/covid-related...

Exercise and a healthy diet can benefit one's state of mind, in contrast.