BTW, I am not disputing you, just playing devil's advocate and wanting someone to challenge my thinking. 

I thought it would be fun to start a thread where we can share our craziest fix-and-flip stories, biggest "oops" moments, and the golden nuggets of wisdom we've picked up along the way.

@Eric E.UBIT only comes into play in an IRA on leveraged real estate and running an active business.

Don't get stuck in the analysis paralysis phase, it's no fun and you don't learn as much :) 

.: I always play it by ear.

This is a very different space than most folks here on BP play in from what I have seen.

Talk to a CPA to see how each scenario plays out.A 401K continues to grow in value, but what do you live on? 

I know real estate is a long term play but you never know when you'll need access to that capital.There are turnkey companies out there that handle the entire process for you from top to bottom so it makes for an extremely passive investment.

Retirement accounts are designed to be invested passively so when the IRS sees you running an active business in it, to level the playing field between retirement accounts and other business the retirement account incurs UBIT. 

lots of fun.