One thing's for sure. If bitcoin hadn't crashed last 2018 the 40k we saw bitcoin hit last year will happen much sooner. But again, I'd side with all the people in this forum. There's no point to lamenting what has already transpired. If amything, the crashed allowed people to open their eyes on the wonders of cryptocurrency and gave them the chance to get in while the price is still not high. The more millionaires the merrier.
I don't think anyone knows the future price of bitcoin, whether it will go up or down and I am sure there are people who invest from 2017 or below, and I believe he is already a millionaire now.
Certain market trends will allow you to make an educated guess on what bitcoin's next price will be. Just because it is highly volatile doesn't mean it is impossible to price speculate as there are methods to do this.