They earn money either through ads or doing paid cam shows online.
Either way, a webcam is a very powerful tool for its price and size.
And yes, those who are willing to pay enjoy the luxury of being able to request things like what position should they do the deed in, what clothes they should wear, among others.
Women who show themselves masturbating on camera enjoy the benefit of not needing to have sex, or even meet those paying men in person just to earn money from them.
Most of these videos are actually private, but oftentimes get released to the public once they break up.