Memory overclock ability, cooler ability, the build quality that can stand 24/7 for months.

I believe ROI largely depends on investment ( how expensive the h/w selling now ) against profit ( how much revenue you get now ). One is still high, one kept dropping. Graphic card stock shortage still remains, while BTC value dip below 2000USD now

BTC value dropped few days back but today rise back. It's not crashed yet.

I guess these miner tried to minimize their loses. If still got stupid miner buying expensive graphic card, there'll always over-priced card selling.

From my limited understanding, nicehash advantage was it will automatically switch whichever more profitable coin/algorithm/pool by itself, so good for those just want to earn BTC. If you specifically targeted ETH then other more dedicated should be better. IIRC my hashrate are better when I test run dedicated miner with nanopool, while nicehash showing lower hashrate.

Cant be, 1060 6GB has more processing unit.

What's the hashrate for each individual ?
Either you have overpowered 1060 3GB and lousy 1060 6GB, or not well optimized mining software.

Hmm, I'm seeing people getting 21MH/s on 1060 3GB and 24MH/s on 6GB, not sure how much they OC. Couldnt get any 1060 6GB card in market to test

Still difficult to get is it ? Got lubang for not-over-priced 1060 6GB ?

Today BTC reaching 29XX USD again, wondering if should buy some if drop low again, and sell at high price point.
What kind of range/increment would needed for this buy and sell to be profitable ? I think those coin exchange service provided charge not-small amount.

I dont know about stock market or forex one, but I was thinking buy low ( $2500 ) then sell ( $3000 ) like that. Got profit ah ?
Then use larger fund buy more, sell again at higher price.

Will that logic work ?

Great just registered at Luno few days back, to prepare for contract purchase at HN

Below are that nicehash calculator, quite close to real life result as I test run for 1 week+.
https://www.nicehash.com/?p=calc

Personally I dont recommend, we missed the timing by many many months. Yes you're still making profit, but consider this, what if the computer koyak ( constant overheat ) with high chances graphic card koyak ( constant 100% load for 24/7, imagine that ), that card along damage RM13XX I think.

My friend's RM1XK 6 cards mining rig, daily profit RM40 per day ( havent deduct electric bill ) I asked her to stop and learn trading, she got RM40 profit by just trading over one tehtarik session Sadly I dont have the capital this month

You probably right as my hashrate are noticeably lower than more dedicated mining program.

Dual 1050 ti could be slightly more profitable than single 1060, but you're running 2 cards, rough estimation that will be 20-30% increase on power consumption.

I had 1070 few months back, test run for 1 week+, profit wasnt high enough ( that time 4.xx USD/day using NiceHash calculator ) for the risk of h/w failure or power consumption, end up sold the card.