Sure, if you want to become a customer yourself.
Your life as a consumer is largely protected from "sharp edges". Predatory practices against you are generally regulated, and you are not likely to face tens of thousands of dollars of liability due to an honest error. It's really easy to "get accustomed to that" and develop a false confidence about your actual risks.
It ain't that way in business. Businesses are the ones responsible for making a safe space for consumers, and are on the hook pretty brutally - that's the only thing that motivates them. Nowhere is that more clear than in the collections business. The industry is simply not set up for casual noobs to dabble in it. Anyone in the space is expected to operate on a large enough scale to justify the cost of learning all the tricks and all the government regs and comply with them. And if you don't, both the government and consumers have a right to come after you.
Are you on top of the credit reporting laws? Debt collection practices laws? Data security laws? Turn your back at a cafe and your laptop is stolen. It has 2000 people's dossiers and social security numbers. A bunch of credit applications get made, bills run up. Who pays for all that? One guess. Or you mistreat a consumer and he sues.
By the fact that you mentioned several types of business, I assume you know the most basic differences. What makes a C-corp, S-corp and LLC different from a proprietorship is the liability shield.
Without the liability shield, you bear personal liability for any torts (civil actions) against you, i.e. Those relating to violating the laws you didn't know about. You can declare bankruptcy, but they would argue to have their court judgment excluded from the bankruptcy, since bankruptcy is not for escaping the consequences of illegal acts.
The cost of the liability shield is a few hundred dollars and careful diligence, so it's false economy to cheap out on it.