The reason to but Bitcoin now is beause acceptance of Bitcoin is increasing day by day along with its value. You will see tremendous growth within a span of 1 to 2 years.
buy now since we can still afford to buy for few next months bitcoin will be so much expensive to buy.
I would say anytime you can buy, the supply is limited yet the demand is increasing, there is nothing to worry about the price
as eventually it will rise, save for long term so you will not panic.
Majority of people lack patience and gets panic very easily when they see price going down and they start to sell their coins at a cheaper price and big whales takes an advantage of buying them at lower price but if you have patience to hold them for really long time then you can buy bitcoins at any stage and at any price as price will eventually go higher in future.