on bitcointalk and most other social media we have two kinds of "prediction"s which you should not confuse them with each other.
1. those that are making a real speculation, doing some analysis and predict it with reasons. in this case there is no 100% correct prediction anywhere in the world. i'd say more than 70% accuracy is the best you can hope for.
examples are more found on
https://www.tradingview.com/s/bitcoin/ than here in my opinion.
2. those that are making bullshit up, adding fake analysis and fake reasons which sometimes make sense too. but they are idiots who are trying to spread some FUD because they wish the market moves in their favor. i'd say their real accuracy is less than 10% and that is only because even a broken clock is right sometimes. but if you check what they say you see them claiming to be always right!
examples: kwukduck, iamnotback and all his alts: Hyperme.sh, CornCube and about a dozen more, freightjoe, shortcoins, also lots of brand new accounts with 0 activity.