Booze is the easiest thing to make money on. The only labour involved is opening the bottle and pouring. My parents were always happy to keep the place open if there was a table of drinkers at the end of the evening.
Buy into a brand that is cool. Not an actual brand like coca-cola, but a cuisine type like Thai or Vietnamese. Those are way more in fashion at the moment than Chinese (bad rep for unhealthiness), but you can make them with the same staff.
Decor and ambience matter more than anything. Being in a fine restaurant is as much about being seen in the right place as eating good food. It's like art; most people can't tell the difference between mediocre and great. But a gallery in Chelsea sends a different signal to one in Shoreditch.
Finally, running a restaurant is indeed difficult. You're competing with people's own cooking, ready-made meals, and every other eatery in the area. Sure, there's three meals a day to sell to each person, but there's also a constant influx of people wanting to give it a go.
I have zero experience in the food industry. But I tell you two things from observation:
1. First, learn where the profit is made. For many restaurants the profits are made with alcohol, not with the food.
2. I have seen restaurants with the most delicious and affordable food bite the dust. It is my impression that in places like NYC you are more in the real estate business than in the food business. Your landlord raises the rent and you are out.
I respect people that run successful restaurants. I think the difficulty is often highly underestimated.