Different groups have different methods of valuing the different types of capital, so the serious engineer example can be someone who has a lot of one type, an an average amount of the other types of capital. Basically just a paraphrasing of the signaling point but a useful model nevertheless IMO.
I never said anything about money being required for social signaling. If you're signaling that you spend a lot of money, then you need to spend a lot of money. There are other kinds of status one signals, money and brands is just one example.
>You think using brands to signal status isn't normal?
We're not talking about social signaling in general. You are the one who mentioned brands and tried to imply everyone was doing it because you can see lots of brands. I pointed out why that was bogus and now you are changing the subject to social signaling in general, which is not the topic.
If, however, you're signaling that you're a serious engineer who doesn't care about fashion, you wear and do other things. This also doesn't need to be consciously considered to still be happening. Ask yourself why so many engineers who work in air conditioned offices wear hoodies but never put the hood up. At the core, social signaling is about saying "I belong to this group" and possibly "I'm high-status within this group". For whatever value group takes on for (the rhetorical) you.
Edit: There's also the problem of it being the fashion, especially outside the fashion crowd, to talk about how much one doesn't care about fashion or signaling. Which is in itself frequently a kind of signaling.