I'm insisting they cannot be solved with money. If every billionaire aimed all their wealth at trying to solve homelessness, they would barely make a dent. If they tried to end child hunger with their wealth, they would barely make a dent. If all it took to fix these things was money, we'd have done it through legislation that commands more economic power than any individual could even dream of, and we haven't, because it takes more than money can buy.
I can quite assure you, aside from perhaps some homeless who are sufficiently dysfunctional that they need specialised care rather than just somewhere to live, the wealth of billionaires could very likely solve homelessness.
The USA has (according to a Google) ~600,000 homeless. Assume an apartment block with apartments having a build cost about 100,000k each, that's $60 billion one-off to build housing, which is but a fraction of Elon Musk's personal wealth. And frankly, they'll be a lot cheaper than 100k each, because they'll be very basic. Of course after that there would be running costs annually, although that would be vastly less - nevertheless I suspect taxing the income of the USA's billionaires by even a modest amount (<10%) could cover it easily.
The thing is, we really can vastly reduce all these problems with taxes that could be raised by legislation. It's just politicians don't want to, and the people whose interests they serve don't want to. The lowest minimum wage in the USA is ~$8/h. Assume a 1600h working year, call it $13,000 p.a. A UBI of $13,000 for the poorest 30 million Americans would cost about $400 billion. That's a lot of money in one sense - but in another sense it's a mere 2% of the USA's GDP. Increase the USA's net tax burden from ~22% to ~24%, that would cover it... and the USA would still have a tax burden lower than the OECD average.
This is one of the weird enduring myths, a sort of appeal to incredulity, that we can't fix these sorts of things. But the numbers say we actually can, were there the political will to do so.