We are one of the wealthiest countries in the world, but this wealth is concentrated in very very very few hands. The US is a country where people are literally terrified of their medical bills.
What's interesting though is that the fund for Boston has reached $30 million, yet only $500,000 for the victims of the Texas explosion. Maybe they would benefit more from the money. Otherwise exactly what you described happens, the charity wealth gets concentrated in the hands of a few.
According to the press, the estimated hospital bills will total $9 million for Boston, which was raised a long time ago. There was an entire community destroyed in Texas.