I apologize if this seems harsh but to me this plan seems insane! You will be so house poor! There will be little money left for cars, travel, life, etc.... Or god forbid severe asset valuation changes!? Also, the cost to build always exceeds budget! Always! We are similar aged and the happiest day of my life was when we sold our $2m house a couple years back... and our net worth is north of $10m. The costs to maintain such a house are excessive. We are in a townhouse now, 1/2 the size and 1/2 the cost, of previous big house, and loving life... but certainly don't feel like our assets are endless even still. I'd move to a smaller house if I could! Having said all that I acknowledge that I put a high value on travel and spend over $100k a year on that but even still I can't imagine spending so much of our net worth on a house.