No you don't need to own your own business or be financially successful.
We do not necessarily measure success in the same way as most people do.
An example that I have used before is this: perhaps you like model railways. It is your hobby, it costs you money to persue your passion.
But you have built a model railway that is the envy of every model railway enthusiast who sees it.
It wins awards.
It's simply about following one's passion to the fullest.
Quite often though, members of the CoS do make money. But it's usually a result of their passion. Not in the pursuit of money itself.
Don't worry too much over filling in the form. We're not looking for the WBC heavyweight champion of the world.
The way you present yourself generally through it will just give us a feel for who you are.
Send the application and just get on with your life. If you present yourself well and make connections with other members that are mutually productive and helpful it will all fall into place.