There is a persistent false claim that Nikola Tesla‘s last words to his mother were:
All these years that I had spent in the service of mankind brought me nothing but insults and humiliation
This claim is a shortened version of an alleged letter written by Nikola Tesla. Perhaps the oldest copy of this letter was posted online in 2015: https://blog.dnevnik.hr/morpheus81/2015/01/1631917462/nikola-teslas-last-letter-to-his-mother.html
Several people have checked the existing Tesla archives and books. One excellent source for letters is a book called “Nikola Tesla -Correspondence with Relatives” published by Tesla Memorial Society.
You probably guessed it: the alleged letter to Tesla’s mother cannot be found from this book. Or from any reliable source about Tesla. The book contains the original letters to Tesla’s relatives and those letters received by him, including telegrams. These letters were written during a 60 year period from 1882 to 1942.
Summary: There is no evidence Tesla wrote these words. Evidence suggests that the words originate from a made-up letter published online in 2015. That imaginary letter also contains plenty of inconsistencies that don’t seem to match with what historians knows about Tesla’s life and last years.