Does it comes down to that by doing the favour I agreed to take all the risks and that she takes all the profits from the whole thing?
Short answer: Yes. That’s why it was a favour.
Longer answer: You didn’t take all the risks; just the ones you controlled. In this case you, not she, decided whether the property would be left in your car overnight, and you made that decision based on your comfort and convenience, not hers. You put her property at risk to save yourself the bother of carrying it up to your apartment.
Note that I’m not condemning your choice; it may have been a perfectly reasonable choice. The risk to her property was a small one - but, unfortunately, it has materialised. I’m just saying that because it was your choice, you have to accept responsibility for the outcome, even though it’s not - obviously - the outcome you wanted or hoped for.
From the point that my choice led to loss of her property it has sense. But it is from this point of view when things already happened. Would it also be my responsability to repay if I for example I took the things from the car to my apartment and then my apartment got robbed?
I'm also wondering what would be the right thing to do if for example I got in a car accident, someone rear ended me and destroyed her property? Would it be my responsibility based on the fact that I made a zillion unrelated choices to be in that place in that time?
Risk of my car being stolen always exists, it could be stolen from me on the road at gun point...etc, risk of someone rear ending me was there also... I think my action did not make any risk bigger, I just missed the chance to make risks smaller, and they materialised.
But what is on my mind now, does it come that I took all the risks and her all the "benefits" from doing that?. In this case my actions had some effect on the outcome of her property loss, but what in case where is no such a situation - things destroyed when someone rear neded me and the driver went hit&run?