do you think its still worth building new machines for mining eth?
i made my first mining rig last week with 5x gtx 580.
Nobody knows when bubble will burst. Just don't buy your GPUs using credit cards and you should be fine.
Silly advice, you get 1-3% rewards with most credit cards, now just don't buy them with money you don't have. Pay off those credit cards monthly.
I am pretty sure most newbies here have bought their rigs with their 20% APR credit cards max out at $20K. Like during the Litecoin days.