The term "freelance" originated in knights for hire. I.e. knights with no lord who would offer their lances to whoever would pay. Essentially a medieval mercenary. Of course mercenaries have been around for thousands of years.
I prefer the term "independent consultant". There are two categories of motivators - one positive (what I gain), one negative (what I'm glad to lose).
In the first category is money, flexibility, multiple concurrent customers so interesting varied work, generous (unpaid!) holiday allowance if I want it.
In the second is the appraisal/target setting/yearly review framework and office politics.