The Girl Who Will Turn 1,000 Play Money into 1,000,000 Play Money into $1,000

PokerStars No-Limit Hold'em, $0.02 BB (5 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

SB ($4.04)
Hero (BB) ($2)
UTG ($7.04)
MP ($1.67)
Button ($3)

Preflop: Hero is BB with K, Q
2 folds, Button bets $0.06, SB raises to $0.10, Hero raises to $0.20, 1 fold, SB calls $0.10

Flop: ($0.46) 7, 3, 9 (2 players)
SB checks, Hero checks

Turn: ($0.46) K (2 players)
SB bets $0.02, Hero raises to $0.08, SB calls $0.06

River: ($0.62) 7 (2 players)
SB bets $1, Hero folds

Total pot: $0.62 | Rake: $0.03

why are we 4betting small pre , then checking behind on the flop. bet nearer pot on the turn. When he's done nthing and been ultra passsive and suddenly comes alive on the river overbetting the pot,it can only be a fold when flushes have got there , 7x has got there, some boats as well.