Well, I had forgotten what Risk is all about. Risk is not a game about taking and holding territory. The game is presented as if that was the smart strategy, and the designer (Albert Lamorisse, a French film director) may even have though of it that way, but it isn't. Risk is about amassing an army that you can use to wipe someone out, so that you can take their cards and turn them in for yet more armies and wipe out the next player, and so on until you have killed everyone off in one long chain of conquest. Victory goes to the one who pulls this off -- or, if that player fails, to one of the survivors who can next turn in a set.
And that's exactly what happened. I played against my sister and her son, any my other sister's husband, son, and daughter. After some messing around in which no one really solidified a position, my brother-in-law saw his chance for that chain reaction, and knocked out first his daughter, then my sister, then me. He had enough armies and to finish off either of my nephews, which would net him enough cards to finish the other one and win. Unfortunately, he listened to my sister's advice on the route he should take through Asia and Australia, and ran out of steam before finishing off the next player. That next player, his son, then turned in a set and took out first his cousin and then his dad for the win.
So, does that mean Risk is a bad game? It is if you want a game that's about taking and holding territory. You can fix this by capping the number of armies you get for a set at 10 or so, or enforcing some other sort of limitation. There have been many revisions to the rules over the years, and the most recent version of the rules doesn't have progressive set bonuses.
Still, what about the original rules? I think they still make for a good game, if you understand what kind of game you're playing. It's sort of like a reversed game of chicken, seeing who has the guts to jump out first. In effect, the game asks you, "Could you win if you got 12 armies right now? No? How about 15? 20?" Then you make your calculations, and hope that if someone else tries before you do, they'll come up short before they kill you. So, sure, you can change the rules to get a different game, but there are a lot of games that are about taking territory. There aren't many that are about constantly ratcheting up the danger until someone makes their grand play.