I think I've heard her say she runs a business and maybe I've heard something about stocks too. But, while possible, I think stocks are highly unlikely.
If the S&P500 increases by 7% each year and she withdraws more than 7% of the total money she has invested each year, she will lose money. If she withdraws exactly 7%, her total money invested will stay the same - numerically - but in actuality, she will still lose money because of inflation, which decreases the value of our money by 2-3% every year. That means she, and the rest of us, can only withdraw up to 4% of a portfolio each year just to have the same "effective income" each year.
Now let's do some math. 4% of one million dollars is just $40,000, not quite enough for her lifestyle. She would have to have a few million already, which at age ~30, is highly, highly unlikely. But if she did have millions already, imo that's still a problem, because then there's no reason to start an OF.