2) All those examples minus one (which I'll get to) people started before the age of 22. That's not "late in life."
4) The example of the person who started running marathons at 84 has broken records "for his age group." Big deal, there's like, what, less than ~5 people in their 80s running marathons in the world?
5) Just because a few people can do it (and that hasn't even been demonstrated) doesn't mean everyone can with a little work.
4) You skipped 3? Ok... so you want 80 year olds who just started marathon running to beat everyone aged 20-30 in their athletic prime? That's actually pretty impressive since those other 80 year olds have probably been running marathons their whole life.
5) I agree. It takes a lot of hard work and sacrifice, and few people are willing to do that. Are you upset that only 10% of people can be the top 10% and that the distinguishing factor is often how hard they work?
You should also look at it this way: For most things, you don't need to be the absolute best in the world, nor is there a way to measure who is the best in the world. Who is the best in the world at software engineering?