Items are not being sold for mats cost, they are being sold for substantially less. The rate at which prices are falling on hundreds of items is to the point that it's not even profitable to buy and desynth the items, because when you list the mats at a profit, more flood the market within days.

The only things that remain profitable, so far, are items which only drop from treasure hunts, etc. (i.e. Dress Material). Outside of that, there is next to no profit in crafting/gathering anymore.

Even with desynthesis it's just a matter of weeks or a couple months at the rate things are going before there's no profit in that.

Unfortunately, S.E. has made crafting so easy they might as well just start everyone at level 80.