I’m pretty sure her mum is a minority shareholder of the top company. They’ve got the Sainsburies dynasty as security to bail them out of trouble.
Not to defend her on what her security net really is but her mom or even her grandparents do not own Sainsbury’s and the family is pretty big so the “sainsbury’s fortune” has been split between multiple people. The family altogether holds a tiny tiny share in the company. Yes they have money and cash and assets but net worth =/ liquid cash. And net worth can not be turned into the same amount of liquid cash fast.
Let’s say my net worth is $20 million. That means I might have about $2 million in cash, the rest is tied up in a stock portfolio, in real estates, pensions and various other investments. You can’t turn these into cash fast or at least not all of them and not without losing significant chunks on your assets.
This is why it is absolutely not a given her family or his for that matter would just toss millions or hundreds of thousands at them to bail them out and this is probably why it was a better option for them to take a loan from a bank rather than take money from family.
it also reflects better that a business managed to get first investors and then the business owners could personally guarantee such a huge loan.