What do you think of me judging my sister for spending as much money as she does?
Why do you think that you need to judge her spending habits?
Because of all the money she has cost my dad
You shouldn't judge her for the money she spends. It has nothing to do with you. It is her money after all.
I'm going to judge her anyway because I want an expensive phone.
When your sister spends her money, she is free to do so just like how when you spend your money, you are free to do so. You could earn some money yourself or ask your father and get that phone you want, without dragging your sister into it!