A lot of people buy solely because they think the halving is some type of guaranteed pump and dump profit.
This is the effect of the hype train. The bull market came earlier than in 2015, so we cant predict how long will be the current cycle. It could end in 2020 or 2022, despite the halving.
Even though it appears that we have transitioned into a bullmarket, the case of a bullmarket is far from closed, which means that there could be somewhere in the neighborhood of up to 40% that the bottom is NOT in. Accordingly, if the less likely scenario were to occur, such as the bottom NOT being in (which is far from non-zero chances), then a lot of bulls will be eating shit.
All of us BTC HODLers should be preparing our selfies, both financially and psychologically for short-term BTC price scenarios that are less likely, without losing sight of the fact that currently, the odds do seem greater than NOT that BTC has transitioned into a bull market (without devolving into fallacious thinking/preparations that our likely current bull market status is 100% or even 80%, when it is likely much lower than that).