Normally, I would say that how others spend their own money is no one else's business, until it starts affecting me personally (e.g. asking me for money, living on my tax money, etc.) But it does drive me crazy when people spend their money unwisely and then proceed to pollute the air with whiny bitching about how they don't have enough money.
However, your approach was probably a bit forceful. You basically told your parents they weren't living right, and that you know better how they should live their lives. Its not too surprising that it didn't go over well. If people think you are attacking them, they will get defensive, even if you are just trying to help, and even if you are the one in the right.
You have to be a bit subversive if you want folks to change and also not to hate you. Start by just being excited about the changes you're making in your own life. Many folks will start to get defensive right there! That would be a clue they are not ready, and further attempts to educate would not be well received. If they express curiosity about your lifestyle changes, its an invitation to discuss in more detail. Refrain from attempting to solve problems that they haven't directly asked you about, even if you think you know better. It will be better if they come up with the idea(s) themselves.
Its not unlike a new religion. If someone tries to push their religion on you, you immediately resist and push back. If that person instead just lives a good life full of integrity, it allows curious people to ask of their own volition and in their own time.