I know exactly what you mean. That's why I put in quotes. It just makes it easier to talk about.
Usually, "dumbing myself down" in my case means suppressing knowledge that I have. I can't fault other people for not knowing things that I do because as you say different people have different interests, and beside that I spend much more time on the internet that what they do, so I'm more up to date with current affairs than they are.
But whether you take "dumbing down" to mean suppression of knowlege, skills or intelligence, the end result is what I was referring to.
> I continue to talk about things that I think are interesting in all company, and when conversation moves in a direction that I don't like, I disengage
This is part of what I mean. Maybe other people have a higher tolerance level (or maybe I do it too much) but this kind of behaviour has really taken it's toll on me.