I’m not sure how much good $250 will do for a child.

I think this essentially explains why taxing billionaires is not very useful, because the total amount of their life generated wealth assets amounts to a small amount for 25 million people let alone larger populations.

Even if you took all the $’s away, the government really needs to tax high numbers of lower income people for the income to be meaningful.

Depends on how it is spent. Buy candy/beer - as many kids will (depending on when they are allowed to access it) and there is no good. Buy some education and it is good. Remember money is fungable - even if this money can only be used for something good, it can still free up money for something bad that in turn destroyes the good (you buy tuition for a semester, but then use your free cash to party and get bad grades...) I don't know how to solve this problem, but it is one everyone should be aware of.

Helping them not go insane from always getting what they want is useful.

It's not either/or. You can tax both the poor and the wealthy at a similar rate.

Taxing billionaires is useful because concentrated power is bad. The fact that it also produces revenue should just be seen as a bonus.