Once again I think Canada has set an example for the world with how to do this properly: permit open and peaceful votes on secession (e.g. of Quebec), treat the issue as something to be resolved politically and not with the use of force, and pass legislation to deal with the matter that: - mandates that the secession question on the ballot be clear and unambiguous; - requires a clear majority to be considered valid;…
There are many wealthy regions in many countries that may want to keep all their money for themselves in spite of the fact that their wealth is based on its historical role within the country as a whole.
For instance, London has a lot of reasons to declare itself independent from the UK. But it would seem rather odd if all it took to secede was a simple majority of people who currently have a London postcode.