Not wishing to kick this conversation to death, but this is the crux of the matter.
Not wishing either to get all idealistic but there is a concept in Bitcoin, like in many other places, called 'community'.
Sharing skepticism about 'investment opportunities' is part of that.
Ponzi schemes are a blight both in crypto and fiat, they are run with the intent to defraud, degrade the investing environment and prey on the vulnerable. Whether you believe that Caveat Emptor should reign supreme is up to your personal values.

By "not minding" about supporting schemes which are likely to be fraudulent, just so long as you make some money, you effectively facilitate them and encourage their proliferation thru greed.
If you're cool with doing that, there's nothing more to say, apart from "being part of the society" does not involve stealing from your neighbour.