Employers let employees fail all the time, and when that happens the stop giving them money. When a startup fails VCs stop giving them money. The illusion of autonomy motivates some people, but make make no mistake - when you take VC money you are an employee of that VC firm - with low pay, no benefits, no title, no desk, etc.

This isn't true in the general case. If you found a startup that's profitable, for example, you have genuine autonomy to an extent that you simply couldn't obtain as an employee, no matter how successful.

This is true in the general case. In the general case a startup isn't going to be successful, the founder is inexperienced and easily pushed around by the VCs, and generally needs to follow their orders to keep bridge rounds, etc coming.

In the rare case of a successful startup, if the board doesn't replace the founder with an experienced executive, the founder probably has as much autonomy as corporate executive in charge of a successful division of a company.