Just when you thought the world had suffered enough in 2017, Mother Nature decided it hadn’t – brewing from 25 August, Hurricane Harvey, a Category 4 hurricane, struck the southern area of the United States, killing 90 civilians and striking up an astonishingly high damage cost of $198.6 billion – despite their growing prosperity and developments in building more withstanding infrastructure, the hurricane was the costliest natural disaster in United States history.
Is this correct usage of the en-dash connecting the sentences within the paragraph this way: informally? It's confusing to tell where the new sentences begin. It's from an informal source though. Capital letters are a rule are they not when connecting two independent sentences with a dash?
What the difference between using an en-dash or an em-dash in this type of usage.