The whole group with Expedia was something around 15k if I recall well. It includes more than a hundred independent brands and products, plus a few massive white labels, covering an order of magnitude more languages and currencies than AirBnb. So better not compare the whole conglomerate to AirBnb (except as an evidence it's bloated).

The last media reports put AirBnb at 12000 or 15000 employees, but the article is mentioning a total workforce of 7500, so either the media were very off or a whole bunch of employees are not factored in. Either way it's a lot, no doubt the business can run with half of that.