I personally have an IUL and added it to my portfolio many years ago for several reasons. The first is the policy allows for an instant Death Benefit from day one creating an instant "Estate" for one's heirs. This is typical with all types of Life Insurance policies but with an IUL the policy owner has the ability to "overfund" the policy by paying more than the monthly premium (cost of insurance) every month which builds cash value within the policy that can grow tax-free over time.
This is where an IUL gets exciting! The cash value gains interest based on the growth of a stock index (such as the S&P 500) and the interest earned is locked-in each year allowing for protection from market volatility. The cash value is never actually invested in the stock market but grows based on how the stock index performs. Once the cash value has accumulated over time and the policy owner needs additional income for Retirement, the policy owner has the ability to take out what is called a Policy Loan from the cash value. Since this loan is not a withdraw, the funds are not reported to the IRS, creating a Tax-Free stream of income during Retirement.