The 73-year-old singer, who organised the original 1985 event alongside singer Midge Ure, told PA news agency he doubted a similar event could take place in the 2020s, "even though your brain is filled with the horror of Gaza or the horror of Ukraine".
The Boomtown Rats frontman said: "I think it's very much of its time, we didn't even expect this to be a thing.
"From my point of view, rock and roll turned out to be almost a 50-year pop, which ended, conveniently for us, with the summing up at Live Aid, then that was subsumed by social media, so whatever's going to happen now will happen through social media.
"Unfortunately, social media seems to be a sort of isolating type medium.
"So could the same thing happen again? Unlikely, in my view unfortunately, when it was mono-media, when you had just essentially two stations in the UK, everyone saw the same thing, which we didn't realise, we saw the newscast, we wrote a song, we thought we'd raise like STG100,000.
"Suddenly it becomes the focus of all that rage and disgust and shame, and that has lasted for 40 years, much to our dismay."
Geldof was speaking at a Wembley Stadium launch event for Just For One Day, a musical, which tells the story of the Live Aid concerts in the national football stadium in London and Philadelphia in the US, on July 13 1985, which were organised by Geldof and Ure to raise money for the Ethiopian famine.
Speaking about the musical, Geldof told PA: "It's amazing that both of us are alive, frankly. But we set out as quickly as we could, I called him (Ure), he was on a rock show, and he said, 'yeah, let's do something'.
"We literally cobbled this song together as quickly as we could, and 40 years later, there's musicals, there's celebrations, there's documentaries all geared towards something that happened here 40 years ago.
"So it's really odd for us, is it gratifying? No, because can you believe there are starving people in the 21st century, it was unnecessary then, it's totally unnecessary now."
Just For One Day will return to London's Shaftesbury Theatre on May 15, with 10 per cet of all proceeds being donated to the Band Aid Charitable Trust.
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