Brad Delong asks how leveraged should we be in the S&P 500?

Brad Delong suggests that a little bit of leverage in the S&P 500 could be profitable. based on the historical math of the S&P 500 simulated with 0-4 levels of leverage (beta of 1 = index fund, beta of 2 = borrow money to double your investment) He has got into publishing the code on a jupyter notebook so we can check his math.  I'm not sure how to actually do this though. Interest rates on options seem high to me. As someone who is in index funds in 403b's and other tax advantaged mechanisms, I wonder how much I can gamble (and at least for the first year it does seem like a gamble) But with a beta of two could I have the guts to gamble real money?

My usual plan is basically Mr Money Mustache - No debt at all, invest as much as possible, currently mostly index funds in the S&P 500 (best and lowest cost though work tax advantaged options) and a little money in Apple (thinking of it more as a dividend stock than a growth stock at this point) and Berkshire Hathoway (as they seem to be the only people who have reliably beat the S&P 500 and I wonder if they have a similar ladder like mechanism to get rid of bad investments better than I would.) The problem is that you only live so long, so to try and use leverage with some safety to reduce the compounding time and a plan better than straight gambling would be good.