@Ben Zimmerman
As I mentioned initially, using IB definitely depends on your financial position and health profile. If you are an accredited investor, you are likely well on your way in your investing career and can utilize IB to fund your investment deals without worry of the 3 - 4 year break even on a new policy. Velocity of capital means always having your capital working for you. IB is one of the tools used to do this. If you are just starting out and have a networth of less than $500K than IB is probably not for you yet.
Using the concept of a 10% average compounded return on some lump sum of capital in the stock market over X amount of years is too basic and unrealistic. Sequence of return risk exists and cannot be predicted with the market volatility.
IB strategy is based on a 4% guaranteed interest (until Jan 2022 anyway) + dividend which typically results in a 5 - 7% real return (tax free growth and tax free use of the capital). That 10% average return in the stock market, applying the lower long term capital gain tax vs short term plus expenses, would be about 7 - 8% real return. That’s basically the same real rate of return for much less risk. For my “safe working capital”, I would rather have it in a non-correlated asset like IB than in a more volatile asset. IB also is based on a private contract with a mutual life insurance company (paying dividends for the last 100+ consecutive years) and holds creditor protection in most states, none of which a brokerage account has to offer invested in the stock markets.
The actual cost of money in an IB policy designed correctly is 0.5% - 1%, which is the difference of the policy loan interest (simple interest) less the guaranteed interest + dividend (compounded) on the policy cash value growth. A policy with 2 - 3% cost of money as you have quoted was not designed correctly. That % difference sounds more like a Northwestern Mutual retail whole life policy with cash value and option for policy loan.
When you buy life insurance, you are essentially buying networth for your beneficiaries. The policy death benefit makes the 3 - 4 year break even period all worth it in itself, assuming you want to leave behind some legacy wealth. I plan on it…