Does raising speaker cables off the floor really make a big difference?

Cable raiser manufacturers also sell a special gas mixture in pressurized tubes which you spray in front of the speakers which increases the frequency response to from -50hz to +1 megahertz. Especially the negative frequencies are of enormous importance to sound quality.
The frequencies above 100k are reserved specifically for the people who can hear the difference the cable raisers make.

Ted Denneys next big thing!

Is it akin to glue sniffing as I think I picked a hell of a week to quit......

I can't wait to launch my business selling the alike.

This little echo-chamber you got going here, I know it must make you all feel normal. But you might want to stop, if only for a second, and imagine how you look to actual real normal people. As a friend told me just today, "Its like they sit alone in their room never bothering to see if anything they're saying is actually true." In other words, mental, deluded... pathetic.

Cable risers are, in general, too low.

They should be high enough for vacuum cleaner/mop to slide under. Convenience with floor hygiene is their most coveted value.

"...never bothering to see if anything they’re saying is actually true."

It is not.