Power
As someone wielding a big, sharp needle over folks of all ages, sizes, and social statuses, you have a huge amount of power for the time they are strapped to your chair with their veins exposed. You will have owners of multi-billion dollar corporations begging you for mercy, as well as movie stars and hot shot producers prostrate under your power (this might be a good time to show them that screenplay you've been working on).
If you are a really good blood sucker, especially on those with difficult veins, you will be highly in demand and patients will ask for you by name.
You could get into a good situation with a fancy doctor's office and bring your incredible skills to their practice, which could lead to a better salary, benefits, and maybe even a loaner of the boss' Mercedes from time to time.
You might even become a Closer or Vein Whisperer—someone who they call in to take over the job after others have tried and failed. Those poor people with bruises and hematomas all over their arms from being treated like a pin-cushion from the less skilled will sing your exalted praises.