How about I cut myself and tell someone about it.
Why are you going to tell someone you cut youself?
Because it makes my parents spend money on me.
Self harming to get more money is selfish. Your parents worry about you and you're taking advantage of them. If they found out they wouldn't trust you anymore.
You should just let me cut myself and take the money.
Betraying your parent's trust like this is a double edge sword. If you need their attention or financial help, learn to approach them honestly and directly. They will want to reach out and help you, parents love and care for their children so much.