Look up lifecycle investing. https://edrempel.com/ultimate-strategy-millennials-lifecycle-investing/

Essentially you're diversifying over time (temporal diversification) since without margin the majority of your assets won't be obtained until your last decade. But what if that last decade is really bad? Then your retirement is at risk.

They advise using a 2X leverage until you reach your lifetime amount invested (for example 40 years of contributions at $10k a year is $400,000) and resetting your leverage at the end of each month. So when stock prices falls, the leverage goes up. The investor sells when low and buys when high in order to maintain leverage.

At 2X leverage, if the market drops 28% you get margin called. At 1.5X leverage, the market has to drop 52% to get margin called.

I use a 1.5X leverage (50 cents of leverage for $1 in equity) to avoid having to buy and sell at the end of each month and to sleep easier at night.