My friend is a locksmith and if your area is not overcrowded and you can keep a good company running it’s really good. People pay a lot of money to get back into their car at 6am but also every building needs a lock and the locks need maintenance.
It’s a real business though as the trade aspect of cutting a key or opening a door isn’t difficult at all. The challenge is running business, accounting and all the certifications and associated protocols. With all that said, it can get crowded real fast so this all only works if you’re one of 3 locksmiths in town at most.
Because it’s believed to be “literal word of god” revealed to Muhammad by an angel word-by-word. Since Allah is perfect and all knowing his word is considered to be flawless and eternal and not open to interpretation or doubt. The theological argument is that imperfect human reasoning will lead to misguidance and thus corrupt the religion so only literal interpretation is acceptable.
So it’s like a constitution that cannot be amended but it’s from over 2 millennia ago when most people didn’t even know how to read or write. It’s a dead end.