Electronic – male-male VGA cable wiring

Don't assume. Most VGA cables use some sort of coax or individually shielded conductors for the Red, Green, Blue, and sync signals. The shields for these signals, which have their own pins, are commonly tied together inside the cable. Additionally, some older VGA cables might not connect the "unused" pins-- which are used on more modern devices.

Computers detect screens by something called Display Data Channel

It's a low rate data signal on four pins in the VGA connector that tells the computer about its presence, allowed modes and frequencies, etc.

You can still use a screen without DDC, but you need some pull-up or pull-down resistors to tell the computer there's a screen at all. You'll also have to force the adapter to produce the signal, and you'll have to set up the monitor parameters manually.