Referenced: https://www.reddit.com/r/Bitcoin/comments/7or8l3/2017_btc_boombust_cycles/
Credit: wotsirB
This is not taking into consideration that Altcoins have gotten more popular/mainstream and the BTC Dominance has been at an all time low. I believe many new investors are buying bitcoin just to get into an Altcoin.
Once Lightning Network and RSK have been implemented, I can see BTC regaining some momentum.