Kem Azlan's post in Convert real column to string formatted column (with dollar sign and thousands separator) was marked as the answer
Ignore formula above. Here is the correct formula:
If(Len(String([REVENUE]))<16,Concatenate('$',If(Len(Split(String([REVENUE]),'.',1))<=3,Split(String([REVENUE]),'.',1),If(Len(Split(String([REVENUE]),'.',1))<=6,Concatenate(Left(Split(String([REVENUE]),'.',1),Len(Split(String([REVENUE]),'.',1)) - 3),',',Right(Split(String([REVENUE]),'.',1),3)),If(Len(Split(String([REVENUE]),'.',1))<=9,Concatenate(Left(Split(String([REVENUE]),'.',1),Len(Split(String([REVENUE]),'.',1)) - 6),',',Mid(Split(String([REVENUE]),'.',1),Len(Split(String([REVENUE]),'.',1)) - 5,3),',',Right(Split(String([REVENUE]),'.',1),3)),If(Len(Split(String([REVENUE]),'.',1))<=12,Concatenate(Left(Split(String([REVENUE]),'.',1),Len(Split(String([REVENUE]),'.',1)) - 9),',',Mid(Split(String([REVENUE]),'.',1),Len(Split(String([REVENUE]),'.',1)) - 8,3),',',Mid(Split(String([REVENUE]),'.',1),Len(Split(String([REVENUE]),'.',1)) - 5,3),',',Right(Split(String([REVENUE]),'.',1),3)),' ')))),'.',Split(String([REVENUE]),'.',2)),'')
