What you're doing is impressive and commendable, no doubt. But imagine if you didn't have any of those friends to give money to - how fo you then know how to allocate your money? Or let's scale up your salary so that you're now a millionaire. How do you divvy up that money in a useful way to your friends that are in need? There comes a certain point where your friends are no longer usefully absorbing money efficiently.
2.5k a month definitely helps out a couple with kids. Now if you increased the amount to 100k a month, would you say they're efficiently spending every penny, or would a portion of that be better spent given to other families? TBH, I think spending 4B in a year is already pretty good considering it takes a lot of time to figure out how to donate in an efficient matter, outside of straight up giving cash to everyone. Otherwise I could easily see these charitable donations getting soaked up by select brand name orgs that just sit on most of the money as a warchest.