Ditto AJ's response.

The only way your idea will work is if you take a disciplined approach to investing, asset allocate, periodically rebalanced and keep all dollars fully invested over the period you'd otherwise be a homeowner. Remember, your equity sits in your house like money in a long term CD. Many will hold this and use it to pay for their retirement condo. Others may keep it to pay for any future long term care while others may keep it as a legacy for their grandchildren. By pulling it out and putting it into the stock market, you are putting it at market risk and default risk (the risk that something would happen to you such that you wouldn't be able to pay it back)

But as mentioned, done correctly, this is not necessarily a bad idea.

BruceM