With all the respect to you, I asked totally different question than your answer.
Guys, the question was:
Maybe someone is a part of such a group and can recommend it?
Many thanks for your opinion thought.
Yeah, that's different answer about your question.
But what is said by @ryzaadit is true... many group of bitcoin prediction is scam and just their own speculation.
If you looking for someone or group with have great bitcoin speculation, I think "whales" is the answer.
Since whales can manipulation bitcoin price and also can know the best time to buy / sell or hold bitcoin.
That would not be speculation - that would merely be a self-fulfilling prophecy (Although i suspect many of these signal groups are self-fulfilling, especially those regarding altcoins.)
Pump & dump groups are much alike to these "Whale" groups.
Just know OP, that if there were any people with sufficient power to manipulate the bitcoin price up to such a degree that you could personally benefit from it, it would in no way be beneficial for them to share that information with you, at any time.
I'd go as far as to say, and i haven't done research into this, (that would perhaps be interesting) that giving signals as a whale (which you will fullfill yourself) only hurts them, unless it's a short squeeze/long squeeze, and you bet with them, not against them. Of course, great levels of confidence would be required and i assume the prisoner's dillema would also apply here, making cooperation pretty difficult.
In regular markets though, that would definitely be illegal.