Whether or not the typical illegal immigrant is more likely to commit crime or not, the fact that so many people are crossing the border unchecked is a serious problem. The overall effect of this is that the United States is importing many problems that are expensive and difficult to deal with. The most obvious of these are the trade of illegal drugs and sex trafficking, but these are far from the only issues.
The core of the rest of the problems lies in the question "Who would choose to deal with dangerous people, to cross the border illegally, in order to be in the United States without any status?" ... The answer to this is people who have no opportunities in Mexico; and this would be individuals who would be the poorest and worst educated people in Mexico. This becomes such a problem because you’re importing individuals who’s prospects within the country are worse than most of the poorest individuals within your country; and these people are not entitled to any form of aid to improve their opportunities.
To put it into perspective, most legal immigrants will have an excellent education and some material wealth and when they enter a country (potentially with some language help) they can meet or exceed the standard of living of the typical individual within the country.
