There are some people - statists, Deep Staters, traitors, etc. - who want this gradual erosion to happen. They tend to get their way in part, because men of good character yield a little here and there because they don't like a particular right. A great example is Kyllo v. United States. Scalia got blasted by War on Drugs conservatives over this opinion, but (IMHO) he was right. You don't shred the 4th Amendment to stop pot. Rehnquist sided with Stevens in that dissent...and then Stevens wrote Kelp< (which gets my vote for worst opinion since Roe) and Rehnquist wasn't there. Well, dude...you're either for a limitation on state power or you're not...this isn't a buffet.
Liberty isn't easy to take...stupid people do stupid things. But the way to stop that is to Amend the Constitution, not water it down. I pray Trump made some right judicial moves to bring things back in the direction you (and I) want.
Also, what was the Massachusetts firearms case you often mention? We may finally have a court that can take up that case.