The insider didn't say exactly how Uber will spend the money, but it's easy to see where the costs will add up. A worldwide mapping initiative will require legions of cars roaming the streets. Also, its deal for high-res maps from DigitalGlobe could prove to be pricey when Uber will need to maintain up-to-date info.
Whatever money Uber spends now may pay off in the future, mind you. The firm isn't shy about planning for a future where self-driving cars are the norm, and that will require extremely accurate maps where autonomous vehicles are both better at safe driving and know to pick you up at very specific locations. And in the short term, in-house mapping would both reduce the company's dependence on Google (important when Google may ultimately become a competitor) as well as boost satisfaction from customers tired of having to guide Uber drivers around confusing building entrances. In that sense, Uber isn't so much gambling with its future as it is protecting its investments.