look 3 months back, 5 USD with 1080ti was normal... than it boosts up to 15...
Who is making $15 per day mining with a gtx 1080ti? the thing is barely making $5 and a gtx 1080 is being sold for $1200, using the calculator + total cost will return your investment in 400 days.
This is a result of timing, and not anything else. People who derided and questioned mining and it's profitability for literally years are now finally figuring out that people have been been making a lot of money doing it. They are late to the party and are paying a premium for almost every single part you need to build a rig because of supply shortages.
I paid $139.99 for my ASUS B250 motherboards, $479.99 for my ASUS 1070Tis, $529.99 for my ASUS 1080s, and 749.99 for my ASUS 1080Tis, they ALL ROI'd in under 8 weeks because of timing.
When you are late to the party, it's impossible to immediately have the same amount of fun as the people who have been there for months/years.
All that being said, a 9/10-month ROI (1080Ti is currently about 285 days mining ZCL) on hardware for mining is still worth it IMO if you are serious about mining.