Reminder: it takes as long to get from 100 to 1,000 as it takes from 10 to 100 -- it is really important to avoid big drawdowns, which 2× leverage is almost sure to produce.

If anything, optimal growth requires fractional leverage, i.e. keeping wealth out of the markets.

For a few years in your '20s, when your investment is going to be small either way, you presumably haven't got a lot of commitments, and you'll have your whole life to adjust for it if a literal once-in-a-century slump happens to hit at exactly the worst time? I can see the logic.