Because they are descendants of the middle and upper classes who benefited from the previous regime and lost everything when Castro came to power.
Right after obama came to cuba there was a large influx of cubans who made the journey through the carribean to the us to gain the guarenteed citizenship [0]. Why would people risk their lives to leave? Are these individuals also upper class escaping slaughter?
[0] http://www.pewresearch.org/fact-tank/2016/08/05/cuban-immigr...
Cuban Revolution was not for a wimp.
It's important to note that even if this elite is the "1%" of the country, this 1% amounts to a significant number of people.