Tibs' notes on PyCon UK 2019 are at https://github.com/tibs/pyconuk2019-notes
Most of the talks (if not all) are available on YouTube.
- Learning - of course
- Networking - making new friends
- Socialising - meeting old friends
- Validation - rebuilding enthusiasm
- Involvement - and paying back
Expanding on those:
Learning: if a technical conference is any good you'll learn things from program items, and possibly also just from talking to people. Sometimes this can be an overview of a new field, sometimes a specific tool or library. I've always come away from PyConUK having learnt at least a couple of significant things. And this is one of the places where lightning talks can shine.
Networking: it's a good place to make contacts within the Python community, and possibly withone one's own field as well. This also includes recruitment (the last several UK Python conferences have had specific recrtuitment sessions, and of course sponsorship acts as advertising)
Socialising: it's nice to meet people you've got to know at previous conferences. For science fiction conventions, this is a principle element of the con, of course.
Validation: there's a grand sense of "I'm doing the right thing" gained from going to a conference of people doing the same sort of thing (whether if be programming C, programming Python, or building embedded systems and doing device bring up). This can revitalise your involvement with what you're doing, and boost enthusiasm in general. Which is a Good Thing, and I think should not be underestimated.
Involvement: it's good to get involved. This can be as simple as representing the company at a recruitment event, presenting a lightning talk (it can be constructed at the last minute!), or doing some session chairing (really, not so hard). Paying back to the conference and the community is a nice thing to do, and makes one feel good as well.
And, of course, if you get involved people get to know you, and that's part of networking...