Capableben:

Why does terrorism continue to linger in the north?

@OP, you should separate the primary and remote causes of Boko haram
The reasons you gave are just the secondary reasons while boko haram strives in the north. I lived in the north throughout my school days and I was opportune to reason with so many young Muslims and their clerics. I lived in kano, Kaduna, zaria, and in about three towns in katsina state. If you go to these core northern states as an adult, you may not understand the ideology behind way of life. I know Hausa's like the back of my palm. For your information, those kids lying in front of your shops are not a mere coincidence. Your safety and well being lies with them.If you treat them well, your stay is guaranteed, otherwise, ....
Now, the primary cause of Terrorism can be summarized as the brand of Islam introduced by Usman Dan Fodio. I don't want to mention the name. Just as you have Born-again' in christianity, so you have this sect. They want to introduce a strict, austere and pure brand of Islam. To them, you are either with them or against them, even if you claim to be a Muslim. They are ready to die for their faith. For this reason, many great northern leaders and clerics are afraid to move against them.The local populace admire and hold them in high esteem because they outspoken, truthful and incorrigible. What led to this book haram today, according to them is the failure of northern leaders to uphold the ideology of Us man Dan Fodio. When these Puritans complain to their leaders, the leaders always use the constitution of Nigeria and democracy as an excuse to persuade them. Meanwhile some members of this sect who used them to become popular will abandon the cause and join the bad and corrupt northern oligarchy.
Example of them are El Rufai, Sanusi Lamido Sanusi, Ibrahim Shekarau, Ali Modi Sheriff etc.
When someone says that the cause of book haram is insecurity, two things are involved, either the person is a Muslim or his teachers are Muslims because they believe that they could help to fight against boko haram if only their security is guaranteed.