(physicist here). I think monktastic1 mostly nailed it, I just want to add some further clarifications. Take the electron double-slit experiment. Suppose no hu

(physicist here). I think monktastic1 mostly nailed it, I just want to add some further clarifications. Take the electron double-slit experiment. Suppose no human checks which slit the electron goes through, but the "which-path" information leaks out into the environment somehow. The interference fringes will be destroyed anyway (called "environmental decoherence"). This is usually framed by saying "oh look, the environment measured the system". In fact, what happened is that (1) you prepared what you believed to be an electron beam in a coherent superposition; (2) you left it open to the environment; (3) you used quantum theory to model the system-plus-environment and predicted that you would not see interference fringes when you check; (4) YOU observed the dots on the glass plate and confirmed that there were no interference fringes. The whole story is told in terms of what YOU believed, expected, and finally what you saw. That is QBism's whole point. Put it another way: in QBism wavefunctions just ARE sets of probability assignments to certain actual events that could be observed. And probabilities are human constructions: we invented them to help us reason about our expectations. So, without humans (or other beings capable of reasoning about expectations), there are no probabilities, hence no wavefunctions either. But stuff still happens, even when there's nobody around to see it or assign probabilities to it. The key conceptual leap is separating "wavefunction" completely from "reality". There's more to quantum physics than just the wavefunctions -- the reality lies in the events that happen, not in the quantum state itself.