Competition is starting to eat into Las Vegas Sands Corp.'s (NYSE: LVS) dominant position in Macau. The company built three massive resorts on the territory's Cotai Strip before most other developers got there, and it had been capitalizing on its early-mover advantage. But in the last few years, Melco Resorts (NASDAQ: MLCO) and Wynn Resorts (NASDAQ: WYNN) have built new resorts there too, and Galaxy expanded its presence.