You'll take the risk of getting caught in volatile markets, because your savings aren't typically guaranteed - true of most 401(k)s as well...
You take all the risk because neither the growth or principal is guaranteed (because most 401(k)s expose you to a potentially volatile stock market)...
Because the financial services industry has neglected to make these little-known strategies widely accessible to the public, fewer than 2% of savers have used an Untaxed Retirement Plan "U-RIP" strategy- while over half of Americans contribute to a "tax deferred" 401(k) or "limited contribution" Roth IRA.