I don't like people here attaching value to it. For me TFTB is simply a person who likes being humiliated/tortured etc but who doesn't like handing over control. There's no better or worse. I just see it as one more flavor in the BDSM scene.

I met a girl last Rubber ball who was a typical TFTB. She was a career girl and didn't have very much respect for men in general, (hard to argue with that one). This gave her exactly what she needed without her needing to stroke some insecure Masters ego. She could focus on herself, and her alone. If the guy didn't like it...well then he should move on. She was a super pain and humiliationslut, so it wasn't some Domme in denial.

We can all formulate theories on why a sub would prefer this. And if they even are subs? But I wouldn't assume it's down to fear of commitment. Rather about priorities in life.