Consider this scenario..

I'm a lead dev of a popular project that has drawn lots of money in the prediction markets for a release goal. I Tweet out that for sure this goal will be reached.. Definitely. This draws a 90% chance on the market that it'll go through.

cont..

I'm getting paid $100k a year but Ive got $50k in the bank The market currently has $1 million dollars staked on it (900k long, 100k short).. How tempting would it be for me to drip that 50k into the market on the short side and throw a spanner in the works last minute?

...

Nothing out of the ordinary shows up in the market yet I'll profit big time.

This is why I think it's unethical for devs to announce their prediction market positions even if you personally think it's good for your own investment in that project.