I really don't have a problem with how many units these guys have or what they did to get them. I also don't want to see caps or any kind of restrictions put in place for anybody.
The game is a business and they spent plenty of money on marketing, setting up servers, and developing the game. I am glad they are getting a return on the investment.
Now, from the perspective of someone who casually spends on the game and plays somewhat regularly. I can say that seeing all of this has devalued what you guys offer in your purchasing packages in my eyes. Is there anything you can do to fix that? Probably not.
I'm just not going to be as inclined to spend moderate amounts of money on something that isn't going to offer a significant improvement unless I do a significant amount of spending.
What I do think will happen is that these guys will eventually get burnt out and become less active and spend less money.
They wanted to put in a lot of money up front to dominate on a fresh server. They wanted to kill a bunch of armies and win a lot of battles. They accomplished that, and I'm sure it was a lot of fun.
However, to maintain that kind of advantage over the long run would get wildly expensive and the development curve will eventually catch up to them. They will go from being super-powered players that have no equal to being part of the stronger class of players that still have to be diplomatic and play within boundaries. They won't be able to best entire coalitions in single combat and they will run into situations that could be potentially devastating to their armies. It's just a matter of time.
If you want to speed that process up then the best advice I can give is to ignore them. It's not going to stop them from attacking anything, but it will give them less incentive to do so. Leaving the capital and cities undefended and holding no pans may not be fun but it's better than the alternative. Which is essentially putting all of your troops they want to kill in one convenient location for expedited extermination.