Final answer:
The primary drawback of a sole proprietorship is the unlimited liability it imposes on the owner, risking personal assets in case of business debts or legal actions.
Step-by-step explanation:
One of the biggest drawbacks to starting a sole proprietorship is unlimited liability. This means that the sole proprietor is personally liable for all debts and obligations of the business. If the business faces bankruptcy or is sued, the owner could lose personal assets. Sole proprietorships do not offer the same legal protections as incorporated businesses, where owners' personal assets are shielded. Hence, while sole proprietorships are easy to establish and manage, the risk of personal financial loss can be significant.