You do, but the pile of investments is either generating income or losing value to inflation, so in practice it's not that much of an issue. You can't spend tax-deferred retirement accounts like a 401k or tIRA without realizing taxable income, and there's significant contribution limits for Roth IRA balances for tax-exempt gains. You can defer capital gains but not dividends, so a large stock portfolio doesn't help you much either.
Plus if you manage your income to stay under ACA subsidy limits, you're generally going to be paying a higher effective tax rate by forgoing tax-deferral opportunities at higher tax brackets in your income earning years or Roth IRA conversions to use up lower tax brackets in your post-retirement years.
Plus if you manage your income to stay under ACA subsidy limits, you're generally going to be paying a higher effective tax rate by forgoing tax-deferral opportunities at higher tax brackets in your income earning years or Roth IRA conversions to use up lower tax brackets in your post-retirement years.
So yeah, it's a pretty big loophole.