Currently, I don't give anything to charity because I believe in taking care of myself first to the point of being FI. I would consider it pure stupidity verging on a moral failure if I was forced to rely on someone else's aid in the future due to my inability to properly plan and take care of myself (such as donating to charity now, but then under-saving and essentially needing my charitable money back later).
Also, I question the effectiveness of charity in general. I don't consider charity spent here in the US to be a good use of money since I think just about everyone here has their basic needs met and has at least some opportunity to get ahead in life, which would leave me with donating abroad where my dollar would also have higher buying power. However, billions have been spent over decades of time 'helping' the poor in Africa, for instance, and yet I don't really see and evidence that that aid has helped make any lasting changes for the better. A lot of good intentions seem to come with negative unintended consequences, and I worry that, such as in the case of many countries in Africa, we are simply perpetuating the status quo and allowing shitty governments to remain unable to meet the needs of its citizens. I would feel much more confident in donating to charities if they produced studies backed with hard data proving the effectiveness of different methods of aid over time.
At the end, though, I do plan to give away my entire stache to charitable or other causes, so I hope to eventually find something I could consider worthwhile. So far, the only 'causes' that stand out to me are micro-lending set ups like Kiva, where I feel that people in need are able to take initiative in bettering their own lives and maybe angel investing in tech companies that may be able to improve technology in the future, thereby bettering everyone's lives. Hopefully, I should have a good 70+ years to think about it more thoroughly and accumulate additional evidence.