- I don't think it should be that hard to figure out roughly how many kids from Singapore get accepted at a particular college, on average, in any year, or for that matter at all of the colleges to which your parents want you to apply. Assume that a few of them have been accepted for some sort of "hook" reason, and some of them may be coming out of elite U.S. prep schools, so have something of a different path in. Then you and your parents should ask yourselves how clear it is that you are among the top x candidates from Singapore. That should give you a reasonably clear sense of your chances.
I suspect the truth lies somewhere in between your assessment and your parents’. I also suspect that protecting yourself from disappointment is at least as strong a motive with you as protecting your parents from disappointment. You should be honest with them about that.
- In truth, you and your parents don't really have different attitudes. You just have a slightly wider view of which U.S. colleges it would be worth paying for vs. NUS, and a stronger sense of the educational benefits of U.S.-style liberal arts curriculum. Those are things on which you should be able to have a rational conversation with your parents. But prepare yourself carefully in advance.
- For what it's worth, when my kids were attending the University of Chicago (5-10 years ago), there were lots of students from Singapore there, many of whom had government scholarships. Far more of them than of students from China, Hong Kong, or Taiwan. My kids certainly had the impression that UChicago was a top destination for students from Singapore.