What did william henry seward want to do?

Buy Alaska for 7.2 million dollars! thats a lot. a real lot. esp bc alaska was mostly uninhabited and unexplored. so. everyone was like yo seward thats dumb and this mistake is gonna be called "Seward's Folly". And now anchorage alaska has a restaurant named that, a bunch of oil, and a bunch of gold. So was this really a folly? I think not 

The answer is crop yield.