Because they know that watching pornography is very addicting and they want to get you hooked so you will buy their videos and pay them money to watch it. Also, these people want to attract young...
Getting into the adult film industry is very difficult however you could work from home as a self employed adult webcam performer. See the link for more information.
If you are over 18, watching porn on porn sites is legal. If you are under 18, being on a porn site is illegal. Some might believe that watching porn when under 18 is okay as long as their parents...