How can I pin a post to my own Facebook profile page?

Yes you can. You just have to be creative. If you want a post to stick to the top of your personal profile page, you just need to adjust the date on all subsequent posts until the end of time, or until you no longer want the post pinned. :)

For instance, you make a sticky post "Welcome to my profile." I'm sure it wouldn't be that Now you are going to eventually post again, which will bump your sticky post down. Facebook allows you to change the date of a post by clicking 3 dots ... in the top right of the post and then clicking "Change Date." Unfortunately, you can only change the date to an earlier data/time, so changing the date on the sticky post won't do you any good. That said, you would need to change the date on the NEW post to an earlier date/time, which would bump the NEW post back down your timeline according to the date/time you set.

Just gotta think outside the box!