With some altcoins having 200%-300% the profitability of BTC, why is anyone even mining BTC anymore?
....
Then the other train of thought kicks in and says YOU IDIOT, that is $600 that could be in your bank account right now!
Because if you want bitcoin to have value, you need to have someone doing the work, keeping the transactions flowing, even if the payout is minimal.
As far as value, GPUs would be a safer bet, they won't decease (or increase) as much as BTC could. But if BTC remains strong, it could just as easily be profitable to just bank the BTC in the long run.