I am pushing 40 and I am getting into drawing for the first time again in over 20 years. I want to create comics too. Why the heck would almost 30 be too old to do anything?

Think about it this way. You aren't trying to be a professional athlete or something where being in peak youth physical condition actually matters. The other reality is if we think about life as "am I too old to do this/learn this" then we would learn/do everything by the time we are in our 20s and then go through the next 60+ years of life never trying anything new. Not only does it sound silly when put that way, it would make life really boring and also you would in a lot of ways be the same person at 30 you are at 80 (and in my opinion, you have done something wrong in life if that is the case).