I've had such bad luck getting to DCA from DC on several occasions in the early morning, like 4:30 or 5am.

A couple of times there were no Ubers or Lyfts available at all.

Then the one one time I tried Curb, it failed me miserably. They contacted me just before the scheduled pick-up to say they couldn't find an available cab to send. I got the impression talking to the Curb dispatcher that they're NYC based and call down to DC to get you a cab. Given that experience I decided not to use them again and schedule directly with a DC cab company.