I don't think girls have dreamed of being exactly webcam models since childhood. Some definitely wanted to be a stewardess or an actress. Perhaps they were attracted by the good money?
You're probably right about making money. In fact, webcam models are also good actresses, so some have a dream come true to some extent. It is also possible that girls like male attention and that is normal. For example, Misasakurai https://recommendedcams.com/models/cherrytv/misasakurai definitely gets it to the fullest because she is young, beautiful and sexy.