Why Bitcoin came so low in 2018 january to march
Not really low. Compare last years January - March and you'll see if bitcoin did really became low from that time up until now.
All the guess people were saying that Bitcoin would touch 25k$ but why did not it happen ?
What are you expecting? Bitcoin will become $25,000 as they said? It's not a hocus pocus that will just turn as they said. Bitcoin is a market that has a lot of ups and downs and is playing just like a roller coaster so basically due to many factors, it can't happen in an instant manner.
Market is constantly moving and price correction can't be avoided. Bitcoin's price may sometimes plunge due to arising issues, negative news, media influence, or misinterpretation of the real nature of Bitcoin. What truly matters is keeping our trust and positivity high and strong despite volatility.