First of all, how do you know what portion of benefits people apply for? If they are entitled to it under the law, and aware of it, what could you possibly feel would prevent them?
Second, people look at it from a perceived benefit vs. perceived effort. Ie, there is a price that they are willing to accept to not work, because work is - by definition - work. So if someone can make $30,000 by doing nothing (making up numbers here for example) it beats making $45,000 and working your ass off.
But if you could only make $15,000 in benefits, working might be far more attractive because of the lifestyle change.
Lastly, there are many developed countries that have absurdly higher youth unemployment rates because of their developed social nets AND lack of work. It's not just one factor.