I think value claims are more likely to be parasitic (mostly concerned with copying themselves or participating in a memetic ensemble that’s mostly copying itself) than e.g. physics claims, but I don’t think you have good evidence to say “mostly parasitic”.
My model is that parasitic memes that get a quick and forceful pushback from reality would face an obstacle to propagation compared to parasitic memes for which the pushback from reality is delayed and/or weak. Value claims and claims about longevity (as in your example, although I don’t think those are value claims) are good examples of a long feedback cycle, so we should expect more parasites.
In many parts of Europe nobody has to work 60-hour weeks just to send their kids to a school with low level of violence. A bunch of people don’t work at all and still their kids seem to have all teeth in place and get some schooling. Not sure what we did here that the US is failing to do, but I notice that the described problem of school violence is a cultural problem—it’s related to poverty, but is not directly caused by it.