There are many reasons why the activity of the game has declined. But that is another new thread and topic.

I don't agree that having a gold farming event on game will increase activity at all, it will increase inflation and not many will be able to afford anything. Let alone the black market players and bots will profit from it all.

As mentioned above there are many ways to farm gold now if you place the effort to farm.

There might be better solutions to your desire to sell your items?