Why are people inflating coins on trade system?

There was a gold squish and finaly gold started to cost a bit more fairly on outland and then you see a guy or few of them putting 4-5 stacks of gold for low price which is just ruiining economy i mean if ur selling under price you just put 1 piece and it sells fast, noone saw... but no they put about 5 of htem and people just start decreasing the worth more and more. Not just gold trade system, auctions to...
I guess some people never got hit by natural selection the way they should have been.

If they are so disgustingly underpriced as you make them out to be, why not just buy and resell for your own profit?