Sometimes you look at a market and you think; That's insane! Who could possibly believe that?!
No longer! I've built a Gemini - Manifold integration where Gemini will play devil's advocate on any position you take.
Try it at https://fergusargyll.site

It uses Grounding with Google search and the experimental URL context tool to read pertinent news articles. I'm currently using the new flash-exp model and I've actually been very impressed with it's arguments thus far, they sound rational and well reasoned.
Sometimes you can get a better argument if you leave the "Your reasoning" section empty - it can give arguments against what it thinks are the best ones.
If you suffer from a severe case of want to go bankrupt-itis, you can get it to reinforce your opinion by pretending you'll take the opposite side.
Enjoy!
@JaySocrates Thanks!
I do think that's one of the better use cases for it - to see if the best arguments sound convincing to you...
Incidentally I love Gems; It's a way for me to save system prompts I want to use often. I even used the "Knowledge" feature for one gem - I'm flight simming so I dumped the C172 POH in there...