Scientific workloads often involve very large datasets. It might be high resolution data captured from various sensors, or it might be more “normal” data but in huge quantities. Assuming the data itself is high quality, larger datasets mean more accurate conclusions.
It’s hard to say. I think it was obvious they planned to use ads and gold to break even, but it took many years to begin monetizing aggressively. Once new Reddit and the app came around, and they started making noise about an IPO, it became obvious.