You might be suffering from the endowment effect. To test this, you could pretend that a friend of yours found $10,000 but had no need for it, and was asking you whether he should give it to you or SIAI. If you would recommend that the friend donate to SIAI, but you choose to add your next $10,000 of disposable income to your bank account, I don't see much of any explanation outside the endowment effect.

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. (This mimics the reversal test proposed by Nick Bostrom.) Remember, the people who are currently holding funds should not in theory have any impact on what your preferred allocation of those funds would be.

(Side note: I think I just realized how powerful the endowment effect is.)