Well, I don't particularly like sports betting, but it doesn't seem worse than any other form of entertainment. Titanic had a 200 million dollar budget in the 1990s to produce about 444,600 movie frames and a bit of sound. Was that a good use of resources?
Though to come back to the main argument: you seem to be comparing Apples to Oranges here?
So the first thing is: how are those companies making money? That could be via Facebook ads, or via sports betting, etc. The second question is: what are those companies doing with the money. That could be investing in eg training neural nets, or returning it to shareholders.
When you invest money, that's the same as spending resources. That's only worthwhile, when in expectation you get sufficiently more resources out later than you put in now.
In contrast, when you return money to shareholders, no resources have been spend. It's up to the shareholders what they want to do with their 'resource-coupons' (ie their money).
From the point of view of Facebook, dividends vs investment both look like spending money. From the point of view of the economy, the former is a mere transfer of resources, the latter is spending of resources.
(You could argue that it's better in some sense for Mr Zuckerberg to control these resources than for the average investor to have that control. I'm sympathetic to that argument, especially if you carefully state what sense you have in mind.)
> On the whole, which is better? What moves the needle in terms of bringing humanity forward?
Dividends only move money around. They don't move the needle one way or another. It depends on what the shareholders are doing with the money.
Btw, Amazon and Tesla show that 'the markets' can be extraordinarily patient with companies that they believe in. It's just that most managers don't have nearly as much charisma. Anyone can (and does!) say they have great long term plans, but it's hard to tell the charlatans from the true visionaries. So as a safe default, markets often prefer hard-to-fake signs of progress, like dividends.