They purchased LinkedIn for $26 Billion in 2016. If it's a purchase that has the potential to impact their business, especially if it could do so throughout their entire portfolio of products/services... they'll make the purchase. In comparison Apples biggest purchase, to date, is still Beats for $3 Billion. I think the current biggest purchase by a tech company is Dell coming in at $67 Billion!
Sometimes it makes more sense to buy an already existing technology than start from the ground up and create your own, especially if you're already behind the 8-ball.