>>9161159Many reasons.
Money is usually, instead of what many thing, the second reason, few of them join porn only for it. After they enter the industry is really difficult going outside, no other job pay so much for unskilled labour force and if you start doing it at 19-20 yo, you probably don't have many other skills. And when you go outside everybody knows you are a pornstarn, if you don't they will know soon, and being hired for any job being a pornstar or a prostitute is very difficult.
The first reason is one:
ATTENTION
Most of those "beautiful" girls probably where not that beautiful in their developing, or at least they didn't fell like they were. They felt like the second choice or the ugly girl of their group, when they see many man whatching them like they are princess they just lose reason. Seeing cameras shooting for them, seeing a lot of people moving where they join the room make them feel important.
That's it.