Because peoples never do proper research for bitcoin and crypto market. Same situation is happen with me but i understood my friends with price history chart of bitcoin also told them many countries are planing to regulate bitcoin saw them articles of newspapers than they accept this will be a big revolution in world's economy.
I think for your friends to understand that with every currency there are pros and cons. it's not the goal of bitcoin. The goal is if bitcoin is to ensure proper decentralization, safe and secure transactions, relatively lower costs per transaction and so on. Profits far outweigh the losses.
Bitcoin is decentralized and ensures holder anonymity. Because of this anonymity, hackers prefer to use this for their own benefit.