well, how much an artist makes is hard for anyone else to judge, but it varies a huge amount between different artists, and people who are upper middle class (which doesn't describe me, but describes many people who are indie fans) are certainly making more stable income than most famous indie artists, even if the indie artist may have access to a larger amount of money all at once, at certain points in their career, which the great ones re-invest in their art (like Grimes) and the addicts invest in drugs or material possessions, and the smart ones who care about money over art (and are thus, mediocre artists usually) smartly invest in the market. Grimes could be quite nicely wealthy today if she'd been one of those boring sensible types who valued money over art, and invested her Visions earnings accordingly. instead, she spent them to make another artistic masterpiece and direct her own videos.

She actually doesn't do much modeling either as of now- except for Stella- otherwise, her "modeling" is just doing press for her albums, and she is photographed in various magazine-provided clothes with designers identified, as part of that interview. It's hard to say where modeling ends and the interview begins- fashion is def something she's always been involved in- including before her career took off. She probably does make a bit of money from that- and it may be the only money she can really count on. But as I said, she has not been the "face" of any brand until Stella with the Pop perfume- so in a sense, that's the first celebrity modeling gig with an obviously huge paycheck that she's had. Whatever money she got for the other photo shoots (where the same magazines usually shot her wearing a huge variety of brands) would not have been gigantic, since those magazines are full of countless barely known models per week.

We don't know about her lifestyle- it's possible she lives in an area that is pricier than she can afford (LA) because that was essential for her career to get attention or maybe just because it was close to her friends or she prefers the climate. I'm not saying there are no ways she could cut down on other costs to fund security (moving somewhere besides LA might be an obvious start). But knowing all these expenses she has, and noticing how little she has compromised, if anything, I was not surprised at all she was having trouble making ends meet. I would have been more surprised if she was managing to make lots of money, even while living in an expensive place and recording all that music and making those videos for three years when she still has zero true mainstream hits, and her supposed "pop" breakthrough album had no hits and charted at #36.