Why shouldn't we buy bitcoin right now?

If I was you I would decide on an amount I want to invest and spend half of it right now.

i don't know others, but i buy the btc.
Well the irony of people is, everyone know to buy low, sell high for profit.
but when market crash like this, everyone start to fear and afraid to do anything, they feared how if the price keep coming down. than they miss the opportunity,or they sell at loss.
The same thing happen when market rise, everyone hyped the price skyrocket, than a lot of people joining the hype, hoping to profit, then they buy at expensive price, end up lose again.