I told him that bitcoin has 21 million supply and he told that this coin also had the same supply https://www.coingecko.com/en/coins/bficoin 
Have same total supply does not mean that B fi coin is Bitcoin.Altcoins can fork from Bitcoin source code but they are not Bitcoin.
How Many Bitcoin Forks Are There? You will be surprised!!!
Your friends should know some basics to do his own research and find scam projects
B fi coin project website has very low traffic: https://www.similarweb.com/website/bficoin.io/#overview. It is very lower than Bitcoin.org website traffic.
https://www.similarweb.com/website/bitcoin.org/#overview
Tell your friend to see difference in trading volumes between Bitcoin and B fi coin: https://www.coingecko.com/en/coins/bitcoin
Note him that Bitcoin is a biggest coin and if your friend visits Coinmarketcap or Coingecko, Bitcoin is a coin listed at top (a first ranking) and it won't be hidden somewhere.