Finally for the $3 or so you might really make per month, you are not taking into account the depreciation of your rigs. You proudly claim my "rigs are paid off" then go on to tell us how clever you are with making a few bucks a month with that equipment. What you fail to account for is that your rigs have value on the resale market and this value goes down each day.
I don't agree with this at the current moment. Basically we pretty much had a crypto crash and many are dumping their GPUs all over eBay and on Craigslist. The prices for mining equipment at the moment is very low. He is basically better off selling the equipment in 6-12 months or so when the supply has been absorbed or "maybe" mining is a little more profitable again.
An RX 470 4GB is going for maybe $70 today, in 6 months it'll maybe go for $100 and maybe in 1 year start depreciating again down to $70. In other words you are better off not selling anything and also not mining either.
I add my two cents, I don't think people will want those old of a GPU in 6-12 months time, at least not for that price. By that time the newer cards will probably be cheaper as well and there might even be a new generation out. From my perspective if I am a second hand gamer I don't buy used just to save a few dollars off retail, I want at least 50% savings.