According to this paper:
https://arxiv.org/pdf/1802.06038.pdf
34k Smart contract have security issues, bugs and are considered a threat.
But the real issue is, that currently no one knows a lot about Smart Contracts.
They are new in the IT business.
Meaning, no one has an idea, how to audit them.
What they did was just poiking 1 million SC and looking at the results.
34k were bad.
But this is not a real audit, this is just trial and error.
Lucky for Steem, Smart Contracts are not implemented here.