I'd like to chime in to counter the common intuitions seen in the other comments.

First, that the more you give, the better it is.
It's known that money has a powerful effect on human psyche, and I strongly doubt that pouring say a million dollar to a charity that is used to manage ~10K$ donations will suddenly multiply its efficency hundredfolds. More likely, that money will be wasted. Or given to local warlords. Or used to pay higher salaries, etc.
The unreasonable assumption here is that there's a direct path from money to utility for other people, as if charities were engines of perfect efficiency that burns money and churns out utility for poor people. Extremely unlikely, even for charities listed top tier on GiveWell.

The second assumption is that charity at all is a good way to spend large sums of money for improving the quality of life of those less fortunate.
I'm reminded of a meme that circulated last year: over the picture of a USB pen the slogan "This has saved more tree than Greenpeace". Kinda true, isn't it?
What if a much better way to improve people's life was to invest not in a charity, but in potentially fruitful R&D?