It's very easy to demand accountability of billionaires and supremely difficult to collectively hold our political leaders responsible. The law doesn't require billionaires to be accountable to the general public beyond obeying laws and paying taxes that are due, but our public representatives have higher standards to live up to, and our focus should be on them, not billionaires. All the wealth of American billionaires would add up to a couple years' federal budgets (or perhaps less than a year of federal and the top 4 populous states' budgets).
EDIT: The City of Los Angeles apparently spends ridiculous amounts of money on a per-person basis to 'solve' the homelessness problem (https://ktla.com/news/los-angeles-is-spending-up-to-837000-t...). This is just one example of ridiculous rent-seeking government bureaucracy and nonprofit hucksters. Money is not the problem, lack of accountability is.