They. Are. Here. Illegally. That they commit a disproportionate amount of violent crime as a demographic is just the icing on the cake. If you subtract the cost of educating them and incarcerating them from the "economic benefit" of them working and paying taxes (which their parents never did), you're looking at a significant loss unless every last one of them is a multimillionaire. 

The poll your 2015 Atlantic article cited was not conducted in Colorado. It's as anecdotal and meaningless to this discussion as me saying "I don't know a single Republican who supports DACA." Which I don't.