Crossing borders is not always a bad thing. In fact, opening the borders of most countries led to globalization, which triggered free trade all around the world. Globalization, for me, is one of the best ideas that people made. It's quite obvious and common sense that people around the world needs different resources. Countries trade service, money, and resources to satisfy the needs and wants of their countrymen, maintaining economic equilibrium in their country. Of course, trading globally is and should be regulated. If not, just like what is happening today and a direct consequence of unregulated trading, an economic crisis will rise and could jeopardize the welfare of the people. When there is economic disequilibrium, illegal crossing of borders happens more often because people wants to stay in a more stable and more prosperous place. Crossing borders illegally could be a worse thing rather than giving you a better life. People take the risks and do this mainly because of jobs that offer higher wages/salaries. In the case of our fellow countrymen, Filipinos that work overseas, called OFWs (Overseas Filipino Workers), go to other countries for them to earn higher salaries. Some of them even used to be white-collar workers in the Philippines. When they worked outside the country, they accepted jobs for blue-collar workers, usually domestic helpers. For illegal crossing of border, some Filipinos stay beyond their limit on a particular country because of the living conditions of such countries. Filipinos that illegal aliens in other countries are coined here in the Philippines as TNT or "Tago Ng Tago". These people are coined as such because they keep on hiding from authorities in other countries that will deport them or even ban them to go to their country.
In simple terms, a country is like a household. In a household, everyone has their own roles to maintain peace and harmony in the house. A household has a leader, usually the eldest and most experienced, which governs all the people and all the work. If you are part of that household, which makes you a contributor to that certain territory, would you just let anyone step inside your house and enjoy its living conditions which you all worked hard for? Of course, not. It is quite common sense that sovereignty and citizenship are both important to a country. Like I said before, people is the foundation of a country. If you can't even determine your national borders and who your people are, then what kind of country are you? That kind of country is just like a hotel where anyone can stay and go.