There was a 7-2 liberal majority during the 1970s. They didn't feel bound by precedent either. That's how we got, for example, Roe v. Wade. (No, there was no precedent for "a penumbra" of privacy giving a right to abortion in any previous court decisions. And whether you like the decision is orthogonal to whether the court was making stuff up completely outside the realm of precedent.)

Conservatives aren't doing something that liberals have not done. Liberals will probably do it again when they have the chance. And so will conservatives.

You don't have to like it, either because it goes against what you want or because you don't think decisions should be made like that. But don't think that this hasn't happened before.