Do you consider cables to be a "component" of your system?

Yes, I do but I need to hear the system first before I put the final tune on it. 

I always upgrade speakers (every 2 or 3 cycles) first, then components, then cables, interconnects, power cords last. This reflects the typical degree of effect on tne sound. Occationally an interconnect or cable will have a large outsized effect… but not typically.

So, over time the interconnects would typically represent 10 - 20% the value of the component. I usually try enough different brands to make sure they sound the best. So, at this point my speakers cost $32K - cables $5K, average component cost $20K, interconnects $3K, and average power cord $1.2K.

I have tried a variety of interconnects. For instance, a $17K interconnect on a $17K component. The difference was subtle but important. I was not remotely tempted because a $34K component would have netted a huge improvement in sound … while tne same investment in interconnect was minuscule in comparison.

They are components.  They are terrible choices for tone controls.

Will your system function without cables?  No.  So they are components.

Will your amplifier function without a fuse?  No.  So it's a sub-component.

Will your speakers function without special footers,  Yes.  So they are tweaks.

Yes, of course.