I think our society became so complex so quickly that our evolution did not keep the pace, we are not designed to remember all the things we have to remember these days. Luckily for us we learned to manufacture "external memories" which are books, notes and blog posts on steemit that work as an extention to our hippocampus (region of the brain where some of our memories are stored). Also the question is not just quantitative, we may store all our thoughts and experiences somewhere in our brains, the problem is also to retrieve these memories. We have a relational access to our memories, which means that memories are categorized by attributes, so every time you evoke a memory it will make other related memories surface, our thoughts work in a kind of tag system. :)