Stop contributing to 401K retirement

Asking for insights and opinion on whether it would be safe for me to stop making contribution to retirement (401K, etc..). Or will I regret it later...

Current balance (401K, Roth, etc..all retirement accounts): approx $500,000 (US) mostly in S&P 500 index fund

Looking to retire in 2040 (15 years)...

Plan to take social security at 67

Quick calc...based on some assumption

  • Initial investment: $500,000
  • Length of investment: 15 years
  • Rate of return: 5%
  • Additional investment: $0

=> $1,039,464.09 after 15 years.

We'd like to divert future 401K retirement contribution to save up for a down payment on a house and 529 college savings plan.