Trying to "Youtube" rewatch talks for most of them. I think conferences can be very unproductive and sometimes are more like a "fun" event than a necessity.
Yes, good conferences are fun. Fun and human connections are important for a healthy community. Hybrids could work; Live stream the talks and gather locally to watch them together.
You make it sound like fun is a bad thing
If your "fun" requires you to produce tons of CO2 then maybe yes it is.