I am in many mediums, like telegram, here, facebook, etc. There is that layer in society, where these people find happiness. And they spread this all the way around whenever they have an opportunity.
No constructive criticism about something, but moaning and complaining. These are the guys who are selling low and buying high and they complain all the time.
I used to turn them down, but it is not easy sometimes. Surprisingly, the listen for rationale and they tend to turn back if they cannot achieve success.
The worst is when complainer is stupid in the same time. You have no chance there, they turn you down from their routine.