Do you profit from the ownership of the toothbrush while it is used by someone else?

That's a completely different thing from what you said at first though. In a state with law and order all rights are protected by violence (for very loose definitions of violence, like incarceration and banishment). I'm unaware of any civilization that has ever existed where that wasn't the case.

You're acting like I asked for a justification of socialism. I just said that the idea that rental property is uniquely protected by violence is untrue. It's also untrue that all property for rent is gained by graft or violence. I know several older people who have rental homes because they took care of the elderly relative who lived in them for many years, that relative died, and they ended up with the house.

Why should someone profit from the needs of others in the first place?

If that's not rhetorical, I think it's because under ideal circumstances incentivising people to use their limited time to service the needs of their neighbors can help to build a cohesive civilization out of a group of highly specialized individuals, allowing the whole group to achieve more than the sum of its parts. It provides the freedom to specialize which is inherently necessary for technological development. The oncologist never needs to worry about starving because he can't build a shelter or grow corn, all he has to do is provide tremendous value to the few of his neighbors who have cancer, and his living will be provided for.

The system obviously comes apart once you move out of the realm of the ideal, but that was the initial premise.