I would guess that a large number of 17 y/os have not been to bed more than 40 times, let alone been to bed with 40 different boys/men. A large percentage of girls at 17 are still virgins and most of the rest have only had sex with a significant boyfriend.
Your friend probably needs to understand that she is seen as a 2+2 easy sluut by the boys. Invest a few drinks, hand her a line or two and those panties will fall down. Look, a good escort charges from $100 to $200 and higher before she takes her panties off. Your friend does not even ask for that level of commitment from the boys and men she is with. Because she is cheap and because she is easy, she will never get a man/boy to invest in her unless she changes her behavior.
We males, boys and men, will invest in you only what it requires to get you to bed. Remember that. And, if you are the right girl, we will invest a lot in you, going so far as to purchase a ring for that certain finger on your left hand and making a lifetime commitment before our family and friends and your family and friends.
Women and girls who do not have sex unless the man is willing to truly invest in them and in a relationship with them find men who are willing to do that. And, women and girls who drop their panties for a few drinks and flattery find men who are willing to pay that price as well. While the woman or girl who holds out for a solid investment in her and a relationship may have far fewer lovers, she will have significant relationships. The women or girl who sells herself cheaply will have a lot of bed partners, but very few relationships. Why make the investment in the girl and relationship if you can get her to drop those panties with a few beers and flattery?
I say this as nicely as I can, but your friend would get more investment in her if she was an escort and charged for her bedroom services. As it is, the guys she's with are probably out a few dollars and they never intend to have a real relationship with her. She either needs to change her behavior and make guys start respecting her by demanding much, much more before she drops her panties or start charging...