Interesting that the GTX 1080 can make that much.
Is this from before the NiceHash hack, or afterwards? Because they were hacked, and all of their bitcoin got transferred out. I lost money from their last supposed payout.
I find it hard to trust them again.
You said "you can make"... are you actually already doing this? You don't have to answer if you don't want to, because reasons, but I'm curious how you felt about the "hack" issue, and whether you would continue to use their service to mine with.
Edit: $300/mo sounds a little optimistic to me. I made maybe $180 the first month, with 2x R9 270x, RX 470, RX 460, and a few other cards, all running, AND doing XMR on the CPU (Ryzen R5 1600l).
It was down to $60-80/mo a few months later, due to difficulty increases. I've stopped due to the NiceHash "hack", and I haven't even made ROI on my RX 570 card I paid $315 for a few months ago.
So, GL if you drop coin on some 1080 cards, hoping to make at least ROI.
So if you haven't actually done this very lately, I would hesitate to tell someone that they could make $300/mo, with only two video cards. Granted, they are quite powerful.
That's with NiceHash. What you can do, is mine (directly, more-or-less, although using a pool is fine) some of the smaller altcoins, and then HODL them, until such time (hopefully) that they increase in value, like we've seen eth do.
OTOH, NiceHash pays in BTC, so just earning BTC and holding it for the eventual rise, is probably going to be profitable too regardless.