First of all, there is no need to force any one to join Bitcoin investment or trading. If your friend isn't interested, it is okay. It means your friend is still not sure about Bitcoin and he doesn't understand the advantages of Bitcoin. He may already learn it, but he misses the part of the potential of Bitcoin in the future. Anyway, even if it is true that there are few people only who have a huge number of Bitcoin, it is never proven that it can destroy the market. We already experienced it for many years, and it doesn't influence much to the market activity. It is just his own assumption because he still doesn't understand enough about Bitcoin.