There are two simple ways to backup only the users and privileges in MySQL:
1- Using mysqlpump utility (as create user and grant statements):
[shell ~]$ mysqlpump -uUSER -p --exclude-databases=% --add-drop-user --users > /tmp/pump-all-users_privileges-timestamp.sql
Dump completed in 1364 milliseconds
Sample output:
[shell ~]$ head /tmp/pump-all-users_privileges-timestamp.sql
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