How Can The French Drink Espresso After Dinner?

I drink coffee at anytime I feel like it and I don't have any problem with it. I am French but I don't think it has anything to do with it. Some people can handle the caffeine some can't. Though I did notice, it is more a French habit to do that. When I was in New York with my ex in-laws, they would always be surprised by me asking for a coffee after dinner and having another one later. I normally reside in Australia and I am usually the only one that will have a coffee late at night.