Why does rebalancing matter if my stocks are doing well?

Because a long bull run quietly pushes your portfolio to a riskier mix than you signed up for. If you set a 70/30 stock/bond target and stocks soar, you might drift to 85/15 — meaning the next downturn hits you far harder than intended, right when you may least expect it. Rebalancing trims the winners back to target, locking in some gains and restoring your chosen risk level. It also enforces a disciplined "sell high, buy low" you'd struggle to do on emotion. The point isn't to maximize returns in any single year — it's to keep your risk consistent so a crash doesn't catch you overexposed. Letting winners ride feels great until volatility returns and your too-aggressive portfolio falls more than you can stomach. Check your drift once or twice a year and act on your rebalancing rule, not your gut.