Now is the best time to buy bitcoin, and hold, because you don't really need a chart to predict that next year will be a very profitable time to sell because of halving.
Just because this happened few times in the past, it doesn't automatically mean that 100% we gona experience the same thing again. Beliveing that next year bitcoin price will pump for sure might make some people do very risky things, like taking a loan from bank.
Despite how halving increases the price of bitcoin to make it more profitable to investors, I'm wondering if it will not lead to devaluing of the currency in every four years? Will the effect of these not be inflation of bitcoin in every four years?
How can it be inflation if rate of how much bitcoin has been mined is cut in half? Based on what you wrote, I don't think that you fully understand what bitcoin havleving is so I suggest you to check a little bit more on the subject.