I despise you, because
I would get hurt if I didn't.
The riddle is refering to marijuana, and to "money" as the one it's calling out. Many industries would be distrupted if marijuana was legalized, hence "money" gets hurt.
Cause you're just a fluffy pastry with sweet filling.
But you're unhealthy vanilla, red velvet, funfetti.
These 2 lines refer to doughnut.
Cause stripped from your banter you lie nakedly yourself.
When doughnut is stripped from its banter(its ingredients), what is left is just dough. Another meaning of the word "dough" is money
Why do you despise me based on my culture and kin?
This refering to dangerous drugs, such as meth and cocaine. Altough marijuana is usually harmless, people judge it unfairly based on these drugs.
Do you hate that I'm sweet in my innermost being?
Dough is not tasty by itself, but marijuana gets you high, without other ingredients.
That I'm a medical miracle providing ultimate relieving?
Marijuana can be used for medical purposes, its most common use is to relieve the pain of cancer patients.
But you pretend to have concern for those you're treating.
Could be a reference to market-based health insurance system in the United States. Money treats patients, but it doesn't care about patients at all. Its only concern is to take patients' money.
Do you know I support people, that some can't walk without me?
Some patients can't even move because of their pain. They need marijuana to relieve this pain.
Why detest the flavorful words of a poet like myself?
This can be clue for "dough"(flavorful words).
Why spit them out so repulsed as if bad for your health?
Some people consider marijuana to be bad for health. They are so against it, they are repulsed by it. Even though it's actually harmless if not abused.
I am not sure about remaining lines.