Chess does become addictive for some folks. In the same way that many gamblers are really more interested in the "action" than the actual result of their bets, I think some chess players develop a need to always have a chess game at the ready. And of course there are lots of gifted players for whom juggling 20 or so games at a time is no big deal. And then it depends on your approach to correspondence chess; some try to craft each game into a personal masterpiece, others treat it like blitz. As to improving? I'm not sure everyone who plays is actively trying to improve. I think there are folks who are just killing time and find chess more intellectually stimulating than solitaire or Angry Birds or whatever. Lots of previous threads on this. Doubt if we'll ever know all the reasons for sure since everyone's life is unique. More of my $.02 from the bottomless jar of pennies. 
Why so many games?
Yeah. When I really want to play NOW I play a 30 min live game.
There may be previous threads on this, but in the 4 or 5 months I've been here, I don't recall seeing one.
A couple of things at work. One is that people log on hoping to play a game and none of your opponents have moved. Lacking patience you start a new game. If you have a day off or perhaps even just a slow day at work, this can lead to lots of games quickly.
The second thing that can happen is someone signs up for a tournament. When those go live you can suddently have 10 new games. That doesn't explain 70+, but can easily move a persons active games from 8 to 18 in one day.
Yeah. I got hit with tournament games last week. I felt overloaded (at 6 games). I won't be signing up for those again.
I mostly play Online Chess. I usually have 3 - 5 games going at a time.
I've noticed that many of my opponents have 20+ games. At the moment, I am playing a game with someone who has 70+ games going.
Why so many games?
Can you actually improve in any meaningful manner like that?