At 1000bb, even against a positional 3-bettor, the arithmetic is merciless: aces raise, everything else calls or folds.
4-bet almost nothing but aces. Even KK often prefers a call — building a 1000bb pot preflop with one pair is a strategy of despair.
You opened middle, the cutoff 3-bet with position. Their range is wider than a blind's — your response widens to match.
Assumes a standard 3-bet; 4-bet to ~2.2–2.5x the 3-bet. Deep, favor calls over 4-bets — a 4-bet pot at 500bb+ commits you with range disadvantage.