So, hypothetically assuming you had said "Yes, I am carrying $2,100 in cash, and will be spending 2 months in NYC and San Francisco", that wouldn't have been a maximally effective answer either. As a young man, their primary worry with you is that you are an immigration risk. If you don't have visible means of support or obvious ties to your home country, then you are probably angling to get a job in the US.

Factors which would not break in your favor here: you're a young man without a family, you are arriving from China rather than Ireland, you had $600 in your pocket and intend on visiting two of the most expensive cities anywhere (which are separated by a $600 plane ticket), and (probably leastly) you think you're going to get money from some shady individual in the US once you get here because of a quirky hawala system that you claim to be a participant in.

Hypothetically assuming one wants to get into the US, "Yes, I'm here for business or pleasure with a defined start and stop date. Here's the hotel reservations and itinerary. Afterwards, I'll be going back to my comfortable middle class life back home in $NATION -- you know, wife, kids, job, a whole bunch of things which are much more attractive than a sudden impulse to live in America. Money? Why yes, I have easily enough money to do what I came to do. If I needed more, I would use my credit cards."