As soon as you see coins with very high staking rewards and APY, it screams scam. It is sad that people still fall for those coins that give high APY. You guys should know that high APY often means high inflation since more coins are being created as rewards and in the long run this could lead to a decrease in value as supply goes up and but the trade volume remains the same (which will always be low for shit coins). Short term, it might be good, long term nope. And also if you see all previous rugpulls and scams, you will see that most of them offered high APY to lure people.
I partly agree with you that those projects which promise a high APY are most often are scam. Their scheme is built on human greed, and it unfortunately works out regularly. But I know several ATOM ecosystem coins that also offer high APY (more than 1000% in the beginning) and you can make good profit with it. But as you said, later on inflation quickly lowered the price and continues to do so. So even if such projects are not scams, it is still not worth investing in them, it is a losing proposition.