Also don't forget that whether or not makeup makes you look BETTER is very subjective, as well as peoples' reactions to it. Some people think makeup, by virtue of being fake and unnatural, looks bad on anyone. There are negative stereotypes associated with people who wear makeup, especially visible/heavy makeup. How many times have people on this forum complained that they're seen as vain, shallow and insecure because they wear makeup? How many times have we also criticized people (especially celebrities) who wear makeup we don't like, or makeup that's very heavy?
So if you ARE into creative makeup, or heavy makeup, and always all about looking as put-together as you can possibly be, the downside is that there are many people - possible employers included - who could view you as insincere (i.e. "fake and plastic"), or trying to hide something, or completely insecure about yourself. It's a double-edged sword.
I'm personally ambivalent about makeup. It's something fun for me, one more thing I as an artist can do to express myself. If someone doesn't want to, I don't assume they care less about their appearance than the person wearing makeup. It all comes down to reasons. The girl wearing makeup might be wearing it because she falls for the beauty industry's hype and thinks all women *need* it, which is absurd. The girl not wearing it might be doing so because she's confident in her natural beauty. (On the flipside, the girl wearing makeup might just really LIKE makeup, and the girl not wearing any might be afraid of makeup or having a kneejerk reaction in response to some stimulus (maybe she's sick of the beauty industry trying to tell women how to look, maybe girls covered in makeup teased her in school because she didn't wear any, whatever, pick a reason).)
But like I said before, I don't think this situation is about makeup but about (as someone phrased way more succinctly than me) your friends not understanding the value of a service. You're not charging for your makeup artist fees, you're trying to cover a small part of the cost of materials you're *routinely* using on them. They don't seem to understand that every time you do their makeup, you have less of that makeup left over for your own use, and it doesn't just fall out of the sky when you need a refill.