Sorry to burst your bubble, but you've got Rowling and Rashford the wrong way round.
Marcus Rashford was helping himself.
That whole free school meal thing was a PR campaign designed to increase his public profile in order to increase his value. He'd signed with Roc Nation who are a PR firm who are open that they use 'activism' to boost the profile of the celebs on their books.
His PR team were looking for a 'cause' to use to boost his public profile and they found one. And they milked it for all it's worth - he got some good sponsorship deals from the PR campaign. He signed with Nike shortly after IIRC and was doing lots of ads.
After all - who had heard of Rashford before his PR campaign? Football fans, and that's about it. After the campaign, he was a household name.
And what has he been doing since? Has he kept on campaigning for hungry kids? Or has he been doing lucrative sponsorship stuff instead?
As has been remarked:
To understand what was interesting about Rashford, and by extension Roc Nation, you had to go to the trade press, and media companies which focused on sports PR. The Rashford campaign was the subject of huge features in AdWeek and SportsPro, and he won PR Week’s “Communicator of The Year” award. What earned Rashford praise from them wasn’t feeding children. It was the exciting way Roc Nation has fused social justice and sport in order to boost Rashford’s profile, the better for him to serve as a conduit for digital marketing operations, the spread of branded content, and the sale of boxfresh trainers.
The bottom line wasn’t doing good; the bottom line, as SportsPro noted, was that during the campaign, Rashford’s Twitter following had grown by 65%, whereas the total social following of Manchester United — which hasn’t run any political campaigns this summer — had grown a sluggish 8% in the same period. Simon Oliveira, a long-term advisor to David Beckham, labelled Roc Nation’s efforts “genius”.
SOURCE: Who’s behind Marcus Rashford? The combination of social justice, sport and celebrity is a lucrative one | Will Lloyd
This is all in contrast to JKR, who goes around funding childrens charities, rape crisis centres, neurology clinics, etc. for 25 years without much song and dance - she gets on with the work of lobbying and puts her hand in her own pocket:
In the 21 years since Vasek’s story was published Rowling has donated £63 million to Lumos, either directly or via the Harry Potter franchise, helping more than 280,000 children not just in eastern Europe but also Haiti, Colombia and Ukraine. All this and much, much more. The Sunday Times calculates that Rowling has donated almost £200 million to three main causes: Lumos, the Volant Charitable Trust and the Anne Rowling Regenerative Neurology Clinic. This has happened out of sight. She rarely gives interviews and has never talked about the full scope of her philanthropy before.
SOURCE: JK Rowling: ‘Nobody who hasn’t been poor can understand what it means’ | The Times
Rowling has done far more than Rashford to help others, particularly children, and she has done so consistently over decades, without fanfare.