Making a porno is easy, just need two or more people (or even just one).
Making a good porno is slightly harder, and probably requires at least three people (two to tango and one to hold the camera).
Making a good porno that people want to watch... well, now things are getting tricky. There's ten billion "two tangoing" free videos out on the net, available for free. It takes a little bit of effort to rise above the mediocrity cloud... hair and makeup people (both face and body makeup), get performers who appeal to as many people as possible, you need an interesting location, you need decent cinematography so you'll need lighting and get enough footage to be able to edit it together... which means you'll need a lot of time so your performers can recover and fill their dance card.
Though there are plenty of people around who get off on being filmed, as far as I can tell, there isn't much overlap between working ladies and porn stars. Usually one is more interested in avoiding publicity, or at least making sure their friends and family don't find out.
