...in the main, they're geeks just like you who a) got good at something and b) started charging appropriate amounts of money for it...
...and c) had sufficient sales skills to make a credible pitch to potential clients or attract clients enough that they made the approach and d) had sufficiently broad understanding of their chosen industry to interact with non-technical people at the client whose problem they were going to solve and e) had sufficient patience, diligence, legal and accounting knowledge, and general acumen to successfully run a small business...
...in their spare time, when they weren't doing what they thought they were actually going to be paid for.
Exactly, but this is actually a specialization of a more generic feature of what my wife has termed "nerds who can talk". Her background is in psychology, but what she's referring to is the ability to function at a high level socially - or in my case, do a reasonably good impression of an extrovert (yes ... it's tiring!)
< e) had sufficient patience, diligence, legal and accounting knowledge, and general acumen to successfully run a small business…
One generally outsources legal/accounting/tax. However, it does require extra time/effort to manage.
Like the saying goes you can work 8hr/day for someone else or 16hr/day for yourself - some of this can be outsourced, but the extra cost/effort never goes to zero.
That is true up to a point, but you still need to make sure your lawyer/accountant understands enough about your circumstances to do their job properly. They are experts in their field, not yours, and they aren't telepathic.
Whether or not you spend enough time liaising with your professional help and checking their work, you're still the responsible person ultimately signing contracts and tax returns, and you're still going to be on the hook if the contract doesn't stand up in court or you get audited and something incorrect is found.
...and c) had sufficient sales skills to make a credible pitch to potential clients or attract clients enough that they made the approach and d) had sufficiently broad understanding of their chosen industry to interact with non-technical people at the client whose problem they were going to solve and e) had sufficient patience, diligence, legal and accounting knowledge, and general acumen to successfully run a small business...
...in their spare time, when they weren't doing what they thought they were actually going to be paid for.