I have every return from the first one I filed in 1966 until 2022. Soon, 2023 will join the pile.
My dad had that back to the 70’s, and upon his death I had to go thru them all because he hid money in files, what I mess. I pleaded with him to get rid of those old files before he passed.
In my case I moved out of the country in 2011 and really had to downsize my files, so I got rid of as many files as I could and digitized a lot of them. Luckily I have these backed up.