Unintended Consequences
That's the thing - they're unintended. This is the story of two decisions, which both had unintended consequences, and which led - one to the other.
William IV was the 3rd son of King George III, and no one ever expected him to be king. But between one thing and another, king he became, when he was 69, and he reigned for 7 years. His biggest historical claim is probably that he managed to stay alive until his niece, Victoria, reached the age of 18, and so could become queen without her mother being queen's regent. Queen Victoria did pretty well for the Monarchy.
Money seems not to have been William's friend. In face, when Parliament - faced with the prospect of no heir to the throne, offered to pay off all of William's debts if he would leave his mistress of 20 years (and their 10 children) to marry