3 days ago i mine 50 WHL per 24h, on 6x1070 8gb. Now is 12 WHL per 24h. The difficulty of mining has grown five times in 3 days, and now WHL mining is not profitable.
At the moment yes. But you can just mine something more profitable and buy back more WHL?! That is smart move!

why would that be a smart move?
if you want less risks it might be better to wait for block 200000 first. moment of truth, to see how things will work out with the 33% to followers (if there is some method to follow somebody by that time) and to see if the social network will be ready by that time?