Re: But they'd still be in jail...
"it's all massive custom ASICs from here on out."
For bitcoin mining, and scrypt that's true.
For ones aimed at GPUs, it's profitable to mine them with GPUs. Depending on your GDDR size, it sems to be Dagger-Hashimoto, Ethereum or one of the LBRA forks.
For the CPU ones like monero, pretty much any modern CPU will make you 50 cents to a euro a day.
I'm using old Dell workstations (Xeon 4/6 cores ~2.5Ghz) with modern GPUs, and they pay themselves off in about ~110 days of operation, with a bit of hand wiggling around depending on what I can flog the spare bits of the Dells for, and exactly what price and chipset and shiny toys the GPUs are.
The popular mining ones (AMD RX 470/480) are a pig to find with decent RAM, but even then a ~280 euro card with shitty RAM produces ~3 euros a day profit, or for a 1080ti a ~750 euro card produces about ~7.50 a day. YMMV depending on undervolting, over clocking, limiting TDP and the efficiency of your PSU.
Never thought ASICs where a good investment idea, high end graphics cards hold their value very well as do efficient PSUs.
AS an example, I just sold a R9 270 for 50 euro, it cost 180 euros several years ago and has produced ~1400 euros (at a cost of ~250 euro) during that time. Still making ~50 cents a day