Networking is a huge benefit, especially if you don't work in a large company with lots of other developers. Sure, the conference and travel might cost a lot but many companies have budgets for this and it does force you to spend the time learning things. If you try to watch a stream or videos while at your regular job, you either probably will never get around to it or you won't give it your full attention.
And for developers it can be a great opportunity if you submit to be a speaker at a conference. It really increases your credibility and speaking effectively in front of a group is a great skill to have.