And the Crypto Andys were all like "you just don't understand DeFi!" to which the retort is "No, you just don't understand finance".
Finance is the way it is for many reasons. There are thousands of years of lessons that have made the system the way it is. I get the innovator mentality of sweeping away the old but there seems to be a fine line between innovation and ignorance.
I'm just sitting on the sidelines watching people relearn all the lessons of finance the hard way, some because they think they understand finance because because they understand merkle trees and consensus protocols but really most just want to get rich quick.
If you believe the statement "if someone is promising you consistent above-market returns it's either a scam or there is unknown or undisclosed risk" it might be true that you don't understand DeFi to some degree. DeFi isn't a single market, it's millions of micro markets that are accessible through what amounts to a single API.
So when you have millions of markets with different returns that can be traded in every imaginable way (and some you probably haven't imagined), throw in an insane amount of dumb money, people willing to borrow at high interest rates (relative to the real world), and a laundry list of factors that introduce inefficiencies into the market, it's quite easy to find pockets of above-average returns if you're smart. I have no idea if Stablegains was actually smart, but it's more than possible to achieve above-market gains in DeFi without exposing yourself to outsized risks.