Years ago, I used to attend tech conferences (Microsoft, San Francisco, etc) and also was a presenter (SAP, Oracle, Las Vegas, etc). With that said, I believe attending a conference in person is not as necessary these days because many of them will have recorded videos.

One can watch recorded videos at 2x or even 3x accelerated speed. One can also fast-forward past the slow typing, the slow talkers etc.

If one wants to go because of in-person networking opportunities, or physically touch some new gadgets (e.g. Microsoft Surface table, etc) that's understandable. However, if one's primary takeaway from conferences is quantity & density of tech information, the conference videos are much more effective for that. For example, O'Reilly sells video packages for something like $499 which is much less than the cost of the registration fee + travel expenses. Microsoft makes their conference videos free on channel9. It's more information for less money; a win-win.