why don't people open high-end restaurants without a dine-in option? As far as I can tell, such restaurants are virtually non-existent.
I'll make my guess. In restaurants, the analogy with "follow the money" is "follow the beverages." For example, if you eliminated sodas at fast food restaurants, my guess is that the profits would disappear.
My guess is that high-end restaurants make most of their money on wine. If they could get you to take out wine at the same price that they charge for dine-in, they would do take-out. In reality, they can't force you to take out wine with your meal, but they can discourage you from bringing your own bottle. So they prefer dine-in to take-out.
Opening a high-end restaurant for take-out only would require you to charge a high mark-up on the food in order to make up for the lost profits on wine.
By the way, there is high-end take-out in Rockville, called Eatzis, and some of the fancier food stores offer what might arguably be called high-end take-out.