As a guy that's been mining for a few years now, I can get behind the idea of mining space heaters. I even wanted to place a small mining farm in the furnace room and then control the vents with individual thermostats to distribute the heat, dumping excess heat as needed.
But mining on a phone, it's just not reasonable. You could put the same chip on a USB stick and it would perform better.
Serious mining makes for some serious heat. If I'm 21 the household heating market is where I would target.
good point
https://soundcloud.com/elux-1/21-inc-embedded-engineer-on-whaleclub-teamspeaklisten to that. its not about making profit. remove the idea of making profit from these chips from your head.

time to dump NXT and buy Bitcoin?

i havnt held nxt for a LONG time.

(read the white paper in my sig to see why, seriously, its written by PhD's, industry leaders and a math god)