Tom's Hardware calculates the RX 580 as making $2.08 per day
The best mining GPUs still promise potential coins to be mined
www.tomshardware.com
but that's with an electricity cost of $0.10 per kWh which is far lower than my actual residential rate.
For argument's sake, let's say my RX 580 would make $1.25 per day -- a far more realistic profit based on my electricity rate. It would take about 18 months worth of mining to pay off an RX 580 purchased at today's street prices.
As I have mentioned elsewhere, the people making big cryptocurrency profits are traders: buying and selling. Remember that 99% of the world's fortune was generated by investments not from ordinary wages or income. If you want to make money from Amazon, don't drive one of their delivery vans: buy AMZN shares instead.
Mining is for people who don't have the confidence to buy the cryptocurrency directly. Mined cryptocurrency is subject to the same price fluctuations as what you purchased on the open market. It's not any "safer", the beta is still the same.
Remember what you are doing when you mine. You are spending some of you cash on a device (GPU or custom chip) and spending more cash to buy electricity to generate cryptocurrency. After just one year's worth of usage, the card won't command much on the used market.
If you cut out the middle man and buy the cryptocurrency directly, you don't sacrifice the expense of a graphics card. If you buy $1000 in ETH and sell it at $1200 you've made $200 plus have your original $1000, and ROI of +20%.
You can't buy a $1000 GPU, make $200 in ETH profits and walk away with a $1000 GPU + $200 cash. The GPU's used value is far lower. Let's say you can sell the GPU for $500; what you have left is $700. Your ROI is -30%.
You're better off taking that money you'd earmark for an RX 580 and buying cryptocurrency on the open market (hopefully at the right time) and swing trade it.