I am quite sure these type of investors love to talk about long term expectations and they won't change their arguments in 1 week down trends.. So bitcoin may go elsewhere, anywhere; above 20000 will happen possibly right before next halving..
Yes, investors like Tom Lee, Tim Draper, and Max Keiser are all long-term investors, a small dip in the price is nothing. the price tomorrow doesn't matter, its the price in a few years is what matters. As for the block halving, I don't think Bitcoin will reach an ATH before it happens. It is likely to happen 6-12 months after the Halving as the market reacts to the half as many BTC that miners put up for sale. Historically this has been the case for the prior halvings.