Be an assassin easy

You can kill being smoke

Killing gets you nowhere in real life, especially when armed forces will be all over you 24/7 until they disable you.

But if you are litteral smoke, they wont

You have to sleep at some point...

But you are still smoke

Ok but they will always follow you and if they can't kill you then they will look for your family

No if i killed my family

Remember in Alabasta, Luffy accidentally crashes into Smoker through many walls when Smoker was unaware?

But if you train your fruit a certain amount(like crocodile) you can transform when attacked even if you are unaware