Why did eBay buy PayPal, when it had spent a lot of money creating it's own alternative? Sometimes the outside party just built a better solution, and it makes

Why did eBay buy PayPal, when it had spent a lot of money creating it's own alternative? Sometimes the outside party just built a better solution, and it makes sense to get a whole company, lots of good staff, good PR and new products in one simple purchase. As long as the return on investment is as-good or better than the ROI of building it yourself, then it's a win in terms of time factor alone.