Importance of booking profits

Taurian: counter-view: by booking profits, we may be throwing the baby out with water.....applies only to investments of course...
Raja Kumar: yes
Raja Kumar: have u read reminiscences of a stock operator?
Raja Kumar: if u sell your long position u have no position
Raja Kumar: in a bull market
Raja Kumar: buttttt
Raja Kumar: here's how it works imho
Raja Kumar: sell excess leverage longs
Raja Kumar: or trim them
Raja Kumar: a bit
Raja Kumar: this puts people in the right frame of mind
Raja Kumar: when u have booked 30-50% of your profit
Raja Kumar: on a trade
Raja Kumar: then u will be willing to move sl to break even or a small loss on remaining
Raja Kumar: and let the market do what it wants
Raja Kumar: but if u are holding full position
Raja Kumar: then u will behave like a manic depressive
Raja Kumar: extremely happy as market swings up
Raja Kumar: and sad as it swings down
Raja Kumar: because emotions are relative
Raja Kumar: to your position
Raja Kumar: if u have sold half then if market tanks
Raja Kumar: u will be 50% happy
Raja Kumar: that its down
Raja Kumar: and 50% sad
Raja Kumar: that u didn't book other half

P.s : By book profits i usually mean book near t2/t3 in a bull market and not at t1 or random points :)
t2=1x target, t3=1.618 target