Indeed, an inventor or entrepreneur bears all the costs of bankruptcy

This premise doesn't seem true (for all that the conclusion is accurate). Our entire notion of bankruptcy serves the purpose of putting limits on the cost of those risks, transferring burden onto creditors. An example of an alternate cultural construct that come closer to making the entrepreneur bear all the costs of the risk is debt slavery. Others include various forms of formal or informal corporal or capital punishments applied to those that cannot pay their debts.