Want another example of what U.S. taxpayers -- including me -- pay for? We pay for the U.S. Centers for Disease Control and the U.S. Army Medical Research Institute. And we U.S. citizens also enjoy at least a right of first treatment from these truly world class organizations.
OK, so why might that matter? Well, consider the recent outbreak of Ebola virus in western Africa. There were a total of 11 Ebola cases in the U.S., but that's not the interesting part for this discussion. (A couple tourists stumbled into the U.S. with EVD, and a couple U.S. nurses were infected when treating one of the tourists.) The interesting part is that 7 of those cases were medical evacuees, mostly U.S. citizens.
Only one of the 7 evacuees died. (He happened to be a U.S. permanent resident and not a citizen, so you can insert your conspiracy theories here if you wish.

He was married to a U.S. citizen, as it happens, and the U.S. government did feel some responsibility. Unfortunately he delayed seeking treatment too long.) Statistically one would expect 4 deaths among those 7, but no, the U.S. government evacuated them from another continent, got them to the world's best facilities, and saved them. My tax dollars at work, again.
OK, but this is Singapore, right? There's no value in having these U.S. government services, is there? Well, in 2002-2003 there were 33 people who died of SARS in Singapore. Let's just say I like having the insurance. I certainly don't ever expect to use that insurance -- I very much hope there's no "SARS II: This Time You Die!" sequel to that movie. We can quibble about how much this U.S. citizenship-based service is worth, but "zero" is the wrong answer.
Of course the CDC and U.S. Army Medical Research Institute aren't selfish. They give priority to U.S. citizens, but the CDC also helps the global medical community save lives, all lives. I pay for that, too. They've made significant progress on an Ebola vaccine, and the world will be a better place when they've conquered this disease fully.
That's not to say that Singapore doesn't have medical researchers, too -- Singapore does! But Singapore cannot possibly match what the CDC and U.S. Army Medical Research Institute can do. There are some inherent advantages in having a big, developed country with much more medical spending. There's also a big advantage in having a big population, because the CDC can (and does) spot rare infectious diseases much more quickly. It's just how the infectious disease math works when you have about 5.5 million people versus about 320 million. The U.S. figured out what was happening with HIV, for example. The CDC notified the world medical community on June 5, 1981, that there was a new infection underway. The U.S. and (later, but soon) France played the most significant roles in understanding HIV and AIDS. The world is obviously a much better place thanks to their efforts -- and, yes, U.S. taxpayer dollars.