We all have to learn from our mistakes. The problem is that sometimes people need a figurative "bop on the nose", a glare and an "Oi! Stop what you're doing!" in order for people to really wake up to themselves, us included.

There are no guarantees that people will listen, but something needs to be said.
Smart people should see it as a course correction, and over time build up their reputations again.

Plagiarism and then lying about it isn't going to pay off long term anyway.
It would have been better if this person tried to make as best quality content as they could, adjusting and making better content over time based on feedback by the community.

Downvotes are a way to claw back ill-gotten rewards, so you reap what you sow.