He doesn’t have to pay a billion dollars, he just needs to be broke for the rest of his life. Screaming “I’m bankrupt” as a way to avoid paying your debt seems a bit hypocritical coming from someone who I’m sure expects people to pay back their student loans in full.
What do you think bankruptcy court is? Some magical procedure where the judge says "oh here let me just ignore all these liabilities you have" and you just walk out after a few hours of proceedings?