"It makes absolutely no sense for terrorists to try the most perilous way into the country, when they have the money and ability to enter the country legally, giving them far more chances to gain entry."
Contrare! It would be much easier for a terrorist to enter this country by crossing our southern or northern border... If illegals can do it by the hundreds of thousands what makes you think a terrorist would have a problem?
Let's see, there's my contention, and there's yours.
I can prove mine, unfortunately it happened exactly like that already, you however, can't because nothing of the sort has actually happened.
There's a 50-50 chance of anyone trying to get into the country by crossing the border illegally being caught, there's a much higher probability of getting in legally, if you have no previous criminal/terrorist connections it shoots up to 100%.