When you buy very deep-in-the-money (DITM) call options, you pay very little premium over the current stock price. The way to use options instead of margined stock is rolling it over every year or two into DITM calls dated a year or 2 further out. Yes a tiny premium you pay for these calls, but then you aren’t paying any margin interest costs. Of course you also have the advantage of not being at the whims of your broker changing the margin requirements on you as they see fit. And another obvious advantage with calls is that you can only ever lose the money you initially paid for the calls, with no risk of any additional losses beyond that.
Another big benefit from using DITM calls, is that in the event of a big downwards move in the stock price, the call value will not fall as far as the margined stock value. As the stock price falls closer to the call strike price, the call starts to gain a larger & larger premium value as it nears at-the-money price.
As an example if you have a $100 Jan 2020 call, and tomorrow for some inexplicable reason TSLA drops $100 in value. The call price will not drop by the same $100 amount, instead it will drop by something closer to ~$70. Meanwhile if you instead had shares bought on margin, they would of course fall by $100 in value.
In the reverse situation, if the stock price instead increased by $100 tomorrow - the $100 call will appreciate in value by essentially the same amount, maybe a dollar or so less perhaps.
So there you have: less of the downside, and the same upside as margined stock.
—- NOT INVESTMENT ADVICE / do your own due diligence etc —-