A 401k loan isn't a cash out. You're basically taking money out of your target fund or whatever, and loaning it to yourself. Right now 401k loans are charging you 8-10% (prime plus 0-2%). That interest is put back into your 401k account. Make sure your 401k provider does loans, not all do. Are you sure $30k is available as a loan? Maximum amount is 50% of vested balance (or $50k). If you take/qualify for a personal loan, you'll likely be paying the bank probably around 6-12%.

If you leave your job while the loan is active, you'll have a short period to pay it off or you will have to claim it as a 401k disbursement with a 10% penalty plus normal income taxes. What are the chances your job changes in the next few years?

What are your minimum payments? What's the expected pay back period? You can do up to 60 months. A 3 year loan payment is ~$975.

I personally feel that is an idea that you should entertain. If your budget can't properly support paying the debt back in a reasonable amount of time, paying thousands of dollars in interest per year. That seems dumb to me. As mentioned, the reasons for accruing this debt needs to be addressed or you'll likely end up in the same situation. There are solid amounts of speculation that the market is flat overall for the next 2-3 years. It's not the end of the world to pay in 9-10% on the money not active in the market while the loan is active.