There have been a number of similar cases in my country, some of them have been discovered by the community and reported to the authorities . That could be seen as a downside to social media fundraising, but we can't just look at a few isolated cases and say that online charity appeals are bad, they need to be banned . Because there are also many philanthropists who want to help others but do not know where to start or not everyone has the ability to spend a large amount of money on charity . Therefore , having an individual/group calling for charity will receive great support from many benefactors as well as help more people in difficult circumstances .
These social media charities are also popular in my country. You will see them giving alms to the poor or helping people who need it with the attention of gaining sympathy and followers on social media. I guess there are people who do it genuinely to help people, but others use the medium to get more money from the public.
"Cost effective"? I don't think that donating money should be considered the most "cost effective" way for someone to gather attention.
Nowadays everyone can become famous by just saying or doing something stupid on social media. This is way more "cost effective" than making donations. Most rich people are already famous, so I don't think that they are donating money out of the desire for attention.
Nobody is supposed to brag about donating money to charity. This shows lack of morals and arrogance, but some rich and famous people think that donations could help them build a better public image of themselves.
There was a time when people were leaking their own sex tapes because they wanted to gain attention. But it is not everyone that can do some of these weird things to get popular. So they just engage in the giving path to gain attention.