I personally don't care how much a model makes per month... unless it is being shoved down my throat in some form. Like models who towards the end of the pay period put up a token goal for the period in their topics, and knowing the math I see it's more than I make in a month. Then I might be less inclined to tip. I'm also less inclined to tip when a model starts complaining about the lack of tips. Like last night, I was going to tip one, but she started going off about how if she didn't get X amount of tokens in 3 minutes, she was logging off, and how it shouldn't be so hard to get that many tokens in those minutes. I moved away from the tip button, then, because I don't need that attitude thrown in my general direction.
But the models who just go with the flow, high earners or not, if I am enjoying their company and what they're doing, and I have tokens, then I'll tip. They may not be OMGBBQHOLYSHIT big tips, but I'll tip if I have the tokens available. I even am friendly with some high earners who get tips from me because I enjoy my time with them. My lower earning friends also get tips from me for the same reasons.
Even models I have never been with before get tips from me if they're doing something I like, or seem to have a good personality. Like last night, a model I had never seen before was playing Skyrim, so I ended up tipping the 20 or so tokens I had on me to her while she played and was asking questions about the game and such. Another model has some awesome Doctor Who posters, so just for those I sent her some small tips for liking Doctor Who when I saw her a few weeks back.
I've even gone into some ACF models' rooms to say hi and just dropped a quick small tip to say hi. Some of them even recognize me from here as soon as I say hi, before I tip.
So, like most, my reasons for tipping are varied. Maybe I just enjoy the model's room/company. Maybe I'm a bit horny and am tipping towards a show. Maybe I just happened to notice her on the homepage and saw something interesting in her topic or on her preview image. Maybe she's playing some music I like (Hi Iris, the anon tip singing the song you were listening to last night was me from the lounge
). If I have the tokens, and they aren't for a private I am planning, then I have no problems tipping, no matter how much the model earns.