@Edward Stephens
Your foregone earnings are absolutely going to be a cost of the withdrawal. You may be able to earn more in real estate, but don't assume that foregone earnings won't play a role.
Let me demonstrate with examples. I'm going to assume you are in the 25% tax bracket, so right off the bat this withdrawal costs you 35% (25% + 10% penalty). I'm also going to assume you are withdrawing $10,000 (you can apply your actual number to the examples below).
Example 1 - You withdraw $10,000 in 2013. Your immediate cost of the withdrawal is $3,500 leaving you with $6,500. Additionally, since the S&P 500 returned 32% in 2013, your withdrawal costs you another $3,200 in foregone earnings ($10,000*1.32). Your cash remaining after the withdrawal is $6,500 and the total cost of the withdrawal is $6,700. How long will it take you to simply break even (a 103% return)? Answer: a really long time (at least 5 years).
Example 2 - You withdraw $10,000 in 2014. Your immediate cost of the withdrawal is $3,500 leaving you with $6,500. Additionally, since the S&P 500 returned 13% in 2014, your withdrawal costs you another $1,300 in foregone earnings ($10,000*1.13). Your cash remaining after the withdrawal is $6,500 and the total cost of the withdrawal is $4,800. How long will it take you to simply break even (a 74% return)? Answer: a really long time (at least 3.5 years).
Example 3 - You withdraw $10,000 this year. Your immediate cost of the withdrawal is $3,500 leaving you with $6,500. Lucky for you, the S&P 500 crashed 10%! Your withdrawal saved you $1,000 in potential losses ($10,000*0.10). Your cash remaining after the withdrawal is $6,500 and the total cost of the withdrawal is $2,500. How long will it take you to simply break even (a 38% return)? Answer: not as long as the other examples, but still a long time (at least 2 years).
As you can see, it's a bad idea. Not only will it take forever to break even, but these examples don't take into account the accumulation of compound earnings that you are missing out on. Additionally, you have to be a market wizard and predict a down market for a withdrawal to even come close to making sense (and it still doesn't).
On top of that, you have to earn around 20% returns (the rough metric I was using to calculate the years in my examples) on your real estate investments - do you really think you can do that as a new real estate investor?
I'm not trying to dissuade you from your real state goals. I LOVE real estate and LOVE the fact that other people want to jump in. But you have to make smart decisions, and an early 401(k) withdrawal is not one of them. It costs too much money. At the very least, stop contributing to your 401(k) but DO NOT take a withdrawal. Create a budget and develop good financial habits before diving into real estate. Investing in a duplex will not solve your financial problems (assumption based on the need for a hardship withdrawal).
"Rule No.1: Never lose money. Rule No.2: Never forget rule No.1." - W. Buffett
Let me know if you have any questions.