If you would recommend that the friend donate to SIAI...

Yes, I would.

Or, for a more radical thought experiment, ask yourself how much of SIAI's budget you would reallocate to your personal bank account given the chance.

I wouldn't reallocate any money to my personal bank account.

I don't see much of any explanation outside the endowment effect.

Okay, maybe I can overcome that at some point. But I think other factors like the predicted reaction of my surroundings also weigh heavily in my opinion.