Don't learn the Perl influenced extensions. You just need POSIX EREs (and BREs for some older utilities) which are simple enough to keep in the head.
"The Insanity Of Linux's Regular Expressions " https://www.youtube.com/watch?v=ys7yUyyQA-Y
All in all, my life would be miserable if I would not have regexp available in grep/sed/editor/ide/java/python, their usefulness trump any such inconveniences.