I doubt it's just because of competition, it's because there is alot more supply now from (Bots, New GWD bosses, new free trade) etc.
Bots are now chopping alot more yew/picking flax/hunting chins which brings in a load of more gp.
New bosses now bring in a load of more gp with these pernix/torva drops.
And now as you get everything you PK, no gold is lost from the game. Like before, if someone lost a AGS that would've been 75M out of the game most likely unless the pker received it which was unlikely, now, the pker receives everything. There's not enough gold going OUT the game