This seems very unethical. The fact that you don't like Softbank or DoorDash or the gig-economy or that you're sending pizza to homeless people is irrelevant. The fact is you're exploiting a bug to personally benefit at the expense of investors.
Why wouldn't you apply the same principals of ethical hacking, where you would notify the party of the exploit?
Why wouldn't you apply the same principals of ethical hacking, where you would notify the party of the exploit?