Is root canal worse than getting a tattoo? during and post procedure? and how long does a rct last?

Not even close!: The only time a root canal is "bad" is when the treatment is delayed and the tooth becomes infected/abscessed. So don't wait. Otherwise, root canal therapy is no worse than a "filling" procedure. Couple of injections for numbing, maybe a third if already infected and"hot." tattoo is thousands of injections! ouch!

root canal treatment: It should always be done with local anesthetic. If you are numbed properly there should be no pain. Slight pain once the root canal is started needs more anesthetic a tatoo with no anesthtetic would be much more painful.

tattoo is worse: A root canal is done for saving your tooth and eliminating an infection that will get worse. A tattoo is a waste of time and money and sooner or later you will pay extra to have that removed. If done properly (better done by a specialist) a root canal is painless and if the tooth is well protected (usually with a crown) it may last for the rest of your life(nothing is guaranteed in life).