Miners are the ones who are most effected by the halving. I am not saying that they manipulate the price, but I will say that it is "oddly coincidental" that around each halving the price tends to rally. Usually after the halving, as the market expects prices to go up at the moment it happens (the market tends to do the opposite of what people expect). The fact is, if prices don't go up, eventually miner revenue/profit goes down significantly and operations start to become less viable to run. If there is a cheaper energy source that manages to power their operations at a much cheaper price, maybe the price won't tend to rally as the cheaper energy source will make up for the change in revenue. I doubt this though. I believe that the halving is one of the economic encodings in securing bitcoin's market value in the long term.