Read all of chapter 10 in context. The writer is speaking to two groups.
Those who are believers and those who are not. Read v 10-22. Sure sounds like security to me.
In v26 this is to the unbeliever. What other sacrifice will forgive their sins, if after being told about Christ, they reject Him and continue in their sinful life?
Yes, v. 26 is about those who reject Christ, those who count His blood a common thing after having been sactified by it (v. 29).
You can’t just change the author’s subject willy-nilly to make him say what you want him to.
You can listen to him or not, it’s your choice. /shrug