The $6,000 quote for Residency usually only covers the initial Residency for two people. This guy also has a couple of kids...don't know of the DGII would "grandfather" the kids under the parent's Residency. Then there are the initial renewal, the 2 year renewal, the 4 year renewal, ad nauseum. With regard to Military Vets getting anything special here, the only thing I ever got (and I'm a retired Navy Commander) was a free parking spot in the Colonial Zone from a DR Army guard because I showed him my ID card! lol
Sounds like his parents are Dominicans, he will get citizenship through them fairly quickly and easily, and his children will get it through him. Only his wife will need to go the residency route, and after 6 months apply for citizenship since she’s married to a Dominican. Won’t cost anywhere near $6,000