Most of them become progressively sluttier because it's the only way to progress, gain fans, and above all keep them.
If a girl keeps showing the same kind of material without getting sluttier, the fans get bored and leave. And the business goes up in smoke. They need to innovate to maintain "commercial tension".
The pattern is always similar. And if you read the comments of what fans ask for it is logical. People immediately ask for harder or full sex, threesomes or fuck with several guys at the same time, anal sex, "black cocks",... More is always asked for.
If you have an OnlyFans account (something you do to earn money) the path always leads you that way.