Postgres replace characters in string

Question

I have column with text where I need to change characters! For example

• �ay----> need to be Day
• �rag---->need to be Drag

So I need to replace � with character D. I try next but I get error:invalid regular expression: quantifier operand invalid

update  tableT pp set descript=(select regexp_replace(descript,'�', 'D') 
FROM 
  tableT kk where pp.id=kk.id) ;

Answer 1

update tableT pp
set descript = (select replace(descript, '�', 'D') from tableT where id = pp.id)

Why don't use replace?