Mining became too expensive due to high electricty costs and greedy asics traders. These equipments are very expensive and after some time they are already worthless to mine bitcoins, as there will be a new asic model on the market as soon as possible.
I believe someday mining will worth again, as we are reaching closer to renewable sources of energy, this way it's one less cost to operate a mining business. However the initial investment has to be huge anyway, and the asics will continue expensive and indispensable.