Killing the goose blindly is just self destructive. We want to them to be able to die, but we need to reduce their size first. That way better options can take up the slack.
Answer me this. Collapse every company worth more than $1B simultaneously. What would happen to the quality of life of those at the bottom? It would be...bad.
You massively underestimate the complexity and fagility of the systems supporting you right now. Food, power and good production would basically collapse.
The biggest problem is the megacorps, they are too big to fail and so need to be broken up. The best way to do that is to make it financially in their interest to shatter themselves. Power law taxes would help both so it now, and keep companies from growing to that level. It also controls the speed of the change, so the supply lines we rely on remain functional.