Engineers should NOT start a business.

I'll say it again, Engineers should NOT start a business... unless they are prepared to run a business. So many people I meet are hungry to "have no boss" and "work on what they want", that they forget that to start a business is to run a business. If you are not willing to "work on stuff that needs doing", then starting a business is probably a very bad idea.

Consider the ideal case. You are an engineer. You love doing engineering. You start a business that is just consulting your engineering skills.

1. Do you think you will always be able to pick and choose your contracts? -Wrong. You work on what the client wants... and if jobs are scare, you take work where you can get it.
2. Do you really think you have no boss?  -Wrong. The client is the boss.
3. No accounting? -Wrong. You now track hours, expenses, invoices, etc.
4. No sales? -Wrong. You have to sell yourself for every bid.
5. No marketing? -Wrong. Every client is a Word-of-mouth marketer for you.

So... by "starting even the simplest business", you've just made a bunch of work that you probably don't like doing.  You've just created a bunch of bosses where you used to have only 1.  And now you are working harder than ever.  So why do it?

1 word: Profit.

The reason you work harder, you do the extra yicky work, etc. is because you can charge WAY MORE than you were before.  As a variable resource, people will pay more for your services. You just have to keep the pipeline of work filled and you will rake in the extra 25-50% due a contractor/consultant.

If you are starting a business for more "freedom", you might get some... but Profit is a far better reason.