TLDR: A large number of migrants don't want, or even intend, to go to Europe. They're deported, or otherwise displaced, and end up trapped in Europe against their will:

“…in the midnight like that her husband put me inside his car… the next day after the drive in the night I see myself near the sea. I don’t even know that sea… He said: ‘Just look at people, if I see people enter inside the boat I should enter’. I start crying, I say: ‘No!’ Because the sea is very big, I was afraid! I say: ‘No, take me back! Take me back!’ The man say: ‘Stay here! …That is the way I enter the boat.”

Those who are in Europe by choice generally say it's because they have no choice:

“Europe is the only place that has the power to protect me, and help me. For me being a refugee is very tiring, because for each of us [it] is better staying in our country, our roots. But here [in Europe] there is a freedom, whereas from where I am from there are dictators, and I don’t have the freedom.”