Some T1's develop ketoacidosis quickly (hours!), others only after a while. DKA is the quick way to die from high blood glucose.
If you're one of the ones not going into DKA quickly because you still produce some insulin yourself, the high blood sugars will cause depression and feeling very unwell on the very short term.
It may also mean the start of diabetic complications, none of which are enjoyable.
It's not only about immediate survival, it is also about quality of life, both short term and long term. For the ones developing DKA quickly it is of course about immediate survival, DKA still costs lives.
Can you tell us some more about why you don't want to take your insulin?