Because most of my friends believe that BTC reached 100,000 US dollars in December, so I want to discuss whether this is true 
Your friends believe are just based on assumption that has no base which I believe is just a mere speculation that has no back evidence to support it. Although, Bitcoin may hit another all time high before end of this year but that doesn't mean it will reach $100k before December ending of this year. Not possible.We had seen on how bitcoin did break those ATH prices which majority didnt really expect for it to be reached or happen?
100k or not then dont hope that much because price is way too unpredictable.There's no way that you would really able to to know on whats ahead.