For investing purpose it is better to wait for bear market.Liquidity is main factor that investors look for this.
i believe you are in the wrong board. the board you should be saying this on is called altcoin speculation not bitcoin.
if you really think when bitcoin price goes down it is a "falling knife" then you never understood what bitcoin is. or maybe you don't know what a falling knife looks like
if you don't believe me you an take a look at some bitcoin charts and see how "these many falling knifes" have ended up. each time there is a drop they are followed by a bigger rally. for example if you bought this falling knife when it went to 3k range you could have made $1500 profit max on each coin.