Strabon also claimed that the Dacians could muster 200,000 warriors ( probably a major exaggeration) as well as Scythian and Thracian allies, making any planned conquest no pushover. And, as we have already seen, Burebista was a shrewd and experienced commander.
Don't be so quick to dismiss an approximate 200,000 host. If they drew predominately career warriors, yes the numbers would be smaller, but even part-timers or past-age veterans could boost it around those numbers, give or take 10-20,000...