Wherever you live, there are likely companies with limited liability of the owners. In the US they are corporations or LLCs or limited partnerships. In your country they may be named differently. See https://en.m.wikipedia.org/wiki/Limited_company.

When such a company runs out of money, nobody else will be required to come up with cash to pay its debts. You don't need to read the bankruptcy laws to verify that, it's just the definition of a limited liability.

What is the point of that, if the money invested is vastly more than what the owner can earn?

The USA having bankruptcy protections is what helps foster this level of risk and entrepreneurship here.

It's not investments that need to get paid back - it's contracts, or rather the value of the contract.

In this case, Xcor would need to pay back the fees they said would go to escrow. Not any investor who took equity on the gamble it would be worth something.

Where is Xcor supposed to get this money? They lost their revenue source, laid off all their employees, and any property they have is presumably not nearly enough to satisfy their debt. The business is almost certain to close pending the resolution of the bankruptcy.

Certainly, if people were promised that there was money in escrow and it wasn't, that sounds like fraud, but that doesn't mean those who perpetuated the fraud have the money either.