Socialism, or rather, the type of cultural thinking, decline, and weakness that Socialism brings. The Romans had their own brand of socialism. Bread and Circuses...
I think VDH's point would be that socialism is the symptom, rather than the cause, of the decline.
In our case, there is an understandable belief that our incredible wealth carries with it a duty toward those who are less fortunate. And to an extent that is correct.
The pernicious part comes when our sense of duty is coupled with a tolerance of, and making excuses for, the abdication of responsibility on the part of those whom our duty calls on us to help. And along with that, there is the expectation on the part of those "helped," that they deserve such help, without questions or requirements.
Add in also the fact that our wealth has given us tremendous leisure time, and the ability to spend money on expensive pursuits and toys and gear for our kids ... and the kids begin to have expectations of deserving rather than earning.
Now you can add in folks who are ardent enough on the topic to make such considerations a governmental issue -- that's where the socialism comes in. But it's only enabled by that cultural sense and expectation of "deserving" help, rather than earning it.