There is no ideal or correct time for investment. Every time is appropriate if you want to invest long-term. Whoever bought at 2017 ATH can sell now and his investment will have been lost, but we can say that this time is the best time to achieve the maximum possible profit in the shortest possible time?
In theory, it is correct, but the price may be in the area between 25k to 32k at some point in the beginning of next year before the upward line continues. Therefore, now is an appropriate time to achieve maximum profit, but it is not the best.
I can agree with what you're saying but if my guess is right and that OP is not yet an investor and just a person that's still trying to find some assurance that this is the right time to get into bitcoin then I got to say that OP should just buy bitcoin now, no more doubting and questions on the cons and pros of buying bitcoin right now, just buy now and hodl for the long-term because if you just keep asking questions and being indecisive with all of this then you're going to end up not being able to buy bitcoin and then the price goes up and then you'll regret not buying because you were indecisive and then the cycle continues until OP loses interest so to OP, buy the bitcoin now and then start asking these questions.