Some words from my own experience as a small business owner/operator from 45 years ago. They're still relevant.
1. People do not like to pay for labor as a line item. They always think you're charging too much. That's why car dealers sell an oil change or brake pad replacements as a job bundle with no breakout for labor.
2. The time spent on "overhead" activities such as getting the customer's information, determining what they want/need, dealing with suppliers, bookkeeping, researching for answers, and on and on, take up a tremendous percentage of the time you spend at and in the business. You will need to earn 100% of your income with about 50 to 60% chargeable time. And don't forget having income to cover time off for vacations, etc. When I tracked all my activities during the day for a week or two once, I discovered that for every 10 hours I spent in the print shop, I was generating revenue, i.e., running the printing press, or taking orders for wedding invitations and rubber stamps, about 4 or 5 hours a day.
3. Social security taxes, insurance, and so forth will eat up probably about 20% of your income. This doesn't include personal income tax. That eats away another big chunk.
4. Making connection with potential customers will a challenge. They don't just come to you out of the blue. Advertising is at best, a crap shoot. And as you may have seen even in this forum, the 15% of customers who are complainers out shout probably 10 to 1 the 85% of satisfied customers.
5. If anyone else in the area is doing the same business, but has an attitude of, "If I can just cover my expenses (pay my rent; make my equipment payment; etc.) I'll be OK," you'll be done for before you even start. You can't compete against someone who is dumb enough to work for nothing. And believe me, they are out there. And as soon as one folds another one pops up.
6. The fewer resources needed to enter the business, the lower the probability of success. The greater the required investment to get into a vocation, meaning time, education, and money, the greater the income one can realize from it. Why do suppose a brain surgeon makes a hell of a lot more money than does the local school janitor?
7. You will need to see yourself as a small business operator first, and a mechanic second. If you love Spyders, and love to work on them, you'll have to make that love subservient to being a business man. Otherwise your priorities will get all screwed up.
The greatest force that keeps small businesses alive is - - - - - HOPE! And you can't borrow money against hope! A great resource for business advice is SCORE, the Service Corps of Retired Executives. They're a service of the Small Business Administration.
https://www.sba.gov/local-assistance/resource-partners/score-business-mentoring. The best part is they don't charge for their consultations.
Good luck with whatever you decide to do. Doing this poll is a good start, but be careful how much you rely on it.