FORKS!
Can't live with them, can't live without them.
Main causes: changes in software or networks, sometimes leading to disagreements. Example: A group of devs can't decide on how many confirmations a coin needs when sending. To solve this problem, a fork could be implemented.
There is usually a predetermined snapshot of the blockchain at a certain height. So, when that block is mined everyone who held X amount of a coin. Then, a new coin will be distributed to all eligible recipients.
With forks, the general public sees this as free money. I see it as an evolution of new technology.
But, forks prove that there is a working system that will simply split up groups of people who do not agree on something within a chain.
Hope I answered your question, there are many ways to answer this one.