The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
The Tenth Amendment addresses powers, not rights. It is much like amending a bill dealing with healthcare, with money to build a bridge to nowhere in some Senators state, in order to get the bill passed. Passage of Article X also kept alive the states right debate. Why the “or to the people” option? After the federal government and states harvest all the powers, are there any left for the people other than the power of protest? Perhaps the Tenth is a haven for lobbyists such as the NRA and political activists such as the Tea Party. For sure, it is a stepchild of the Bill of Rights. For sure, it is like that bridge to nowhere.