I agree with this, but such a belief is neither a necessary nor sufficient condition for good choices. Girls that believe this still have sex, because they also want to have sex and what people want now often trumps what for their future. Girls that don't believe this often have less sex than those that do, because other socialization and opportunity factors play a bigger role. IOW, such believes play a minor role of making reckless sex choices somewhat less likely. Also, even when they play a role they often do so not by making them choose abstinence but by making the girl want to use birth control and avoid ruining their future via pregnancy. Thus, highly available and free birth control is an enabling condition that allows these beliefs to have optimal impact in connecting these beliefs to actual behaviors that reduce some of the harmful outcomes of sex.
Also, the modest role of such beliefs doesn't speak directly to the role of education, because it is likely that overt "education" has minimal impact on these beliefs. Beliefs, especially regarding personal agency and goals, are a product of many many interacting factors, of which overt efforts to instill them are a tiny contributor. Thus, "more education" is a tiny contributor to this beliefs which is itself only a very modest influence on sex choices, and part of that influence depends in a positive way upon contraception availability.
So, the notion of limiting contraception choices and opportunities in favor of educating such beliefs is absurd is likely to produce more harmful actions.
Ah, yes: girls just cannot wait to spread their legs, bear every medical, physical and social consequence of early sexual involvement with guys who care only about getting off. This is evidence that they are enlightened.
No, girls "can" wait. They just choose not to, because they also have a sincere non-coerced interest in sex itself and in the various social factors that surround it.
And most girls that care about and think they can control their future still choose to have sex, and no amount of "education" is going to eliminate that fact, even if it does have a small positive impact on where, when, how, with whom, and how often they have it.
Who needs birth control? Certainly not boys. Boys don't get pregnant so it's not their problem.
Only you are creating the false dichotomy between birth control for girls and other useful things like education and birth control for boys. You starting by attacking the idea of free long-term birth control options for girls under the false notion that it undermines the benefits of education or of developing birth control for boys.
The reality is that the consequences for boys are there but inherently less than for girls. Boys don't wind up with an growing organism inside their body that threatens their health whether they keep it or abort it and alters their body chemistry and inherently creates and emotional attachment that will either constrain their options or potentially cause them psychological harm if they make certain choices. No matter what ideal culture we try to manufacture to make things more "even" these will always be true for girls and not boys. Also, the reality is that we have a pervasive culture that is slowly morphing but not going away anytime soon that puts more expectations on the mother than the father in terms of childcare and career/job sacrifice. It is even likely that natural maternal attachment is stronger, thus even if the culture radically changes mothers will feel more pain and guilt about work-caused separations. Girls do and always will suffer greater negative consequences from unwanted pregnancies, and future limiting options from wanted pregnancies. Thus, it is cruel and stupid not to offer them ever opportunity possible to avoid those pregnancies, regardless of whether they choose to have sex.
After all, girls WANT to have sex with random guys who will dump them
No, girls want to have sex, and during the decision point, they want it more than they want to guarantee that avoid the merely hypothetical potential negative outcomes at some future point. Thus, they choose to have it.
In fact,why waste any time or effort or money into educating girls? Let them pop out as many kids as the boys can manage,
No one implied of the sort. You are the one arguing against their access to contraception and thus make any girls that choose to have sex wind up popping out more kids. Educate girls as much as possible. They will still have sex, even when its a bad long-term option, and if you don't give them more access to more effective birth control options then even that limited educational impact will be even less effectual in preventing pregnancies.