In fact, they are infinite.
In the 1860's, the United States ceased, for all intents and purposes, operating as a constitutional republic, and began operating as a centralized deep state oligarchy.
Theoretically, you are correct, they should be infinite, if, we were still following the Constitution, but we aren't, it is just a pretext, a ruse, to mollify the masses.
That fact of the matter is, yes, the civil war WAS about slavery, but the
Casus belli, was the federal government's violation of the state's sovereign rights. There is no prohibition in the Constitution against states succeeding from the Union, so?
According to the 9th amendment, as you say, the rights of the states, and of the people, should, hypothetically be "infinite." That is a right that the founders felt was reserved for the southern states if they could not resolve that issue peacefully. The northern industrialists were offended and put out, by the sheer economic scale, and the lack of economic development that did not take place because of slavery. . . the northern oligarchs didn't care anymore for the poor, drafted cannon fodder of the civil war, than they did about the black man.
Nor did the oligarchs back then, care about the damage they were doing to the constitution back then, anymore than our leaders do to ours, every day now. Back then. . . they destroyed the protections of the 9th.
Today? Our generation's leaders?
The leaders we have today, no matter the party, are busy destroying the protections of the First. During the pandemic, no gatherings, stopping some from protesting, no religious ceremony, and folks just accepted that. Now, there are some websites the government actually blocks you from visiting. . . I shit you not. . .