Because her career failed and she also had problems with her agency contributing to her bad image. She was never a nice person to begin with, she just had mediocre skills and a mediocre walk to go with compared to top models like Vlada and Tanya. She's also known for her super skinny body and not being very versatile (body wise), it doesn't appeal to commercial where money and fame come. Plus her instagram is cringeworthy lol. She also aged terribly since her late 20s, I guess a diet of cigarettes and water doesn't help.
It's also really tragic because apparently Snejana married some famous Ukrainian guy who is known in mens boxing industry, who definitely also had bad criminal ties. He mentally, physically and sexually abused her for years, and took extreme control of her life, leaving her with no freedom at all.
The constant abuse started affecting her career, and she stopped being cast after that, because the industry assumed she stopped taking modelling seriously. Though it's interesting to this day, still, the way she expresses having no interest in modelling even then. Apparently, Snejana ended up in New York for longer than expected and cared only going there for a "good shopping" trip, she was then somehow spotted by Steven Meisels team and he demanded her for a photoshoot.
(
There's an interesting, very authentic and no BS interview with Snejana on YT about this marriage situation and how her career started and deteriorated. It's in Russian but has English subtitles to anyone who's interested)
In reality, Snejana's biggest desire was to date these classic post-Soviet, mafia bad boys and recieve expensive cars, it seems. She almost describes modelling as a fortunate "cool, high-earning odd-job" for her, at the time. It's still sad though, she regrets every ounce of it. I believe the "diva" attitude comes from a very harsh and traumatised childhood.
Sad to admit, but Snejana's story is a classic narrative of these models who were born in the USSR right before the collapse - I also believe Ruslana Korshunova had similar fantasies to Snejana - they get involved with these rich criminal men, and end up getting abused or murdered by these guys, thereby ruining their lives.