To see what they're like live? Because it's entertaining?

trust me my friend.....mase is correct......as you well know i love seeing bon jovi,i'd go every week if i could,but of all the dvd's and tv concerts i've seen i've only enjoyed one

Right, fair enough, but obviously other people like watching concerts on tv, hence live dvds/cds selling.

Not to mention someone might not get to see their favourite bands live so this is what they have to do. An inferior way to experience it but necessary in some occasions.
I mean, it's not as simple as what Mase said.

For the record, I don't even really watch concerts. I've seen and enjoyed a few though.

i think its the buzz you get while 40'000 people are going mad for it in a stadium.....and your right in the middle of it

Unfortunately I haven't gotten to experience any bands live except for one I didn't know. It wasn't a great performance (it was free as well...) but I ended up liking the songs.

first chance you get you should try someone big that you've heard of in a stadium......trust me you wont regret it

Stadiums are overrated I find

And I've been to a few concerts which would have been better watched on DVD, because of poor vision, poor acoustics, or just the fucking muppets don't know hot to set up their sound right.

stadium gigs rule...nothing like them

Well tbh I would choose the 100 odd people in a small town hall watching Davy Graham any day to when I went to Wembley Stadium to see Muse, it's not even close for me. And the Muse gig was very good.