Self-determination is a fine concept as long as the majority of people support the existing government. If they don’t, then it’s a dangerous insurrection. From Ryan McMaken at mises.org:
Opponents of secession in the United States often choose from several reasons as to why no member state of the United States should be allowed to separate from the rest of the confederation. Some antisecessionists say it’s bad for national security reasons. Others oppose secession for nationalistic reasons, declaring that “we”—whoever that is—shouldn’t “give up on America.”
Antisecessionists Believe Self-Determination Leads to “Bad” Laws
One of the most popular reasons to oppose secession is that people will pass “bad” laws in places allowed to live under their own governments. That is, we’re told that without federal “oversight” over state and local communities, independent states would deny basic “rights” such as getting an abortion, voting without ID, or guaranteeing that every cake-shop owner is forced to bake cakes for same-sex couples. These independent governments, we are told, would also fail to enforce “progressive” regulations such as bans on fossil fuels and paying workers a federally imposed minimum wage. Therefore, the story goes, these places must be forced—by military means if necessary—to comply with the US government’s mandates and regulations.
Yet far more tolerance is extended to the rest of the world—a place composed of 190-plus independent states—where governments adopt their own laws. Only in a select few cases—think Russia, Iran, and Syria—do we hear that the US government must intervene to ensure—by force, of course—that people in these parts of the world adopt the “right” laws. Everywhere else—as in Peru, India, Canada, or Poland—it’s perfectly tolerable that laws be set locally in accordance with local values. we are told. Those places are democracies, after all, and we’re told democratic institutions establish “legitimate” government.