They can build up a huge treasury/economy from War Profiteering
I haven't played as the Drath yet, but that answers my question. In my current Suicidal game as Terrans, the Korath (whom I set personality to Generic so they would expand, and was forced to war with from killing their leader incident) went from flying around measily 30 Attack 30 Defense fleets, to having 900+ Attack 100 Defense fleets in about a year and a half.
In the beginning I got 5 other civ's to declare war on them. This included most every other civ except a few, including the Drath,. But I recently checked the Drath treasury during a diplomatic sit-down, and by all that is mighty (and the war of All vs Korath has been going on for about 1 year and a half), they had some crazy amount of BC! Never seen an AI have that much, it was 326000+ if I can remember right. 1/3 of a million.
The thing is, Drath are weak, their military stinks, but after Thalan surrendered their empire to them (from the Drengin butt-kick they received), they will probably hit the million mark eventually.
I would trade my Influence points for it all, but having to do that in 100BC increments is not how I want to spend my whole Saturday today.