Big-G tells me that "platitude" means: a remark or statement, especially one with a moral content, that has been used too often to be interesting or thoughtful.
He was asked: What do you think the greatest threat to humanity is at this moment?
And responded:
There are some things that aren't likely but we should worry about - nuclear bombs and bioterrorism (from nation states or terrorism), or a big pandemic. This is the 100th anniversary of the Spanish flu and if it came back the amount of travel would make it spread faster than it did last time.
Once you get past those threats then the biggest question is global cooperation to avoid climate change and reduce the risk of war. It is disconcerting to see a rise of countries turning inwards and not investing in alliances which have helped us avoid big wars since World War 2.
Climate change is a real test of how we can work together globally since it is a complex problem where major changes need to be done well in advance of the big harms.
With a link to: https://www.gatesnotes.com/2019-Annual-Letter?WT.mc_id=02_25... (a 431-word expansion on his thoughts on climate change)
I don't think any of his responses have fit the definition of "platitude".
I think an example of a "platitude" would have been the response: "War, we need to give peace a chance!"
There are a lot of very wealthy philanthropists, and I think that's because people seek meaning in their life once they no longer get benefit from earning more.
Conversely I could name on famous multimillionaire frequently in the news these days, that has a track record of treating charitable foundations as tax dodging piggy banks. So there are all sorts.