Can anyone explain me what that type of behavior is? This is some sort of magic trick that help you selling more or just that person has some sort of mental illness?
All those level 13 are placed on auction in ark by one person.
[MEDIA=imgur]1hSCS1o[/MEDIA]
There is goldrush in ark, probably there is much more mining there than usual which means more sells.
Mayhem ends so probably even more peoples heading there at today.
I mean I know, but look at the prices of those level 13, they are placed on auction by the same person and he set price at 138% then he goes down with amps to the 129% 
What’s the problem exactly?
He’s created a price ladder.
He is probably trying to figure out where the max and min price is. I usually sell plates at the start of mayhem events and during migration. If you are the only seller and the items fly out the door, I would look to increasing the MU to see what the market will accept. Nothing wrong here in fact the market is working as it should. The Gold Rush involves crafting and mining. Maybe he crafted a few hundred amps and wants to ensure he sells or uses them all before the end of the event (which does not last very long )
Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts (an obsession) and feels the need to perform certain routines (compulsions) repeatedly to relieve the distress caused by the obsession, to the extent where it impairs general function
In this case the individuals obsession revolves around ladders and or stairs
There is a gold rush crafting events,so, guess him sell amps for no profit just to be competitive in event.
or far more likely .. there was a second person and they were having a price war, and teh second person removed their level 13 to under price the other person. Happens all teh time
Well some of you dont know how much competition was between level 13 crafters 
There were periods when they sold months in loss to remove other crafters
Thats how you drive a Trend up
People will buy cheapest first and end up buying highest last
After highest Was bought you can set the “New” lowest price to the old “highest” price
Much more efficient then Listing for lowest price
Edit* thats rly a low amount of amps in there , me alone culd dry the market for the day… use them all up and i wuld have to wait for supply again