you do not think correctly. Chech ethereum profit calculators. With the increase in network hashrate,increase in difficulty due to the dirty bomb and the value which is half what it was 2 months ago, you are wrong. Even a 1070 will net less than a dollar a day after electric cost.
People are stupid or want to be stupid, mining is not a simple thing, hardware breaks, warranty in most cases dont work, problems occurs like thunders, lightning strikes and you lose all the hardware, you need to replace and buy new ones, some of them will break within 2 months, some within 3 months and so on, so people should never calculate what estimates tell them too and if they do then they are stupid. A ROI of 12 months means 24 months ~ 48 months and in most cases they will not get their money back at all.
Soon the difficulty will increase drastically because of ice age.