I like the idea of higher collateral. Two, I don’t know any retail investor who regularly makes money trading with margin.
1) Lending investors money is a huge profit center for B/Ds.
2) Traders buy more stock and thus pay higher commissions.
3) Losses mount up faster as inexperienced traders are reluctant to take consistent small losses.
4) Excessive debt is at the heart of every blowup and meltdown in history.
If you don’t know how to trade, by god stay away from margin. You’ll lose your grubstake much faster than otherwise.