It seems a lot of consultancies follow this pattern:
1. Hate permanent job.
2. Start consultancy.
3. Spend half the day finding work/collecting bills; other half programming.
4. Eventually find reliable client with long-term project always pays on time.
5. Cancels all other contracts to focus on reliable client.
6. Go to step 1.
The way to break free from this is to scale the consultancy by hiring developers and profiting on overhead. This was not mentioned in the post, but if you neglect the scale factor, it will be very difficult to break past a typical employee salary. There are only so many hours in the day. The alternative is to sell a product.
I think your post is a little misleading in that #1 implies working for BigCo on the first read-through, but then working for yourself on your own business stuck with a single major client on the second read-through.
Perhaps some people will find this equivalent, should both stakeholders (BigCo/single demanding client) be equally unpleasant, but I for one still see a lot of value in having full control over my life and my time.
Of course, then you aren't writing code, you are building a business and doing sales and recruiting. Which is fine, if that is what you want, but most folks who are technical probably want to focus on technical services.
Both trying to charge more than typical employee salary as a solo consultant and scaling a consultancy business have their own difficulties.
Personally I’d find it more difficult to try to scale up my consultancy business rather than just convince the client that I provide results that are worth more than what they’d normally pay their own people to try to provide.