How do we stop from becoming a crazy old person as we grow older? Why do people become this way as they grow older?

I've been noticing this with people around me. As we all grow older, they keep getting more paranoid, scared, crazy, and so forth. They, who were once free thinking kids are now very slowly turning into the people they absolutely hated - without apology.

For most of them, I think the biggest transition was when they started having kids. All of a sudden, that nice innocent thing that they as a kid were alright is now the most dangerous thing in the planet. Worst of all, they are now starting to support politicians and lawmakers to create arbitrary laws not because of any real threat but because of these stuff they fear. The enforcement they spew is even more scary. Things like "lock them up for life!"

What's happening to them? Why are they turning out this way? How do I make sure I'm not heading the same path they are?