The PSAT doesn’t help you get into college. You’re very unlikely to get a scholarship out of it either – your scores have to be very high to qualify and your eventual college has to participate in the program, which many top schools don’t. So why does the PSAT exist? Marketing.
Schools want to recruit students with specific attributes (ethnicity, geographic region, academic interests). The PSAT collects this info from students and sells it to schools. Then they can send you lots of flyers and letters and emails.
What you get out of it is a preview of your SAT score without having the score appear on your official record. The scores are quite accurate. You can easily convert them to ACT scores. And with these scores you can make an educated guess about your eventual SAT: about the same as your PSAT if you don’t study and about 200 points higher if you do.