A huge one is massively pragmatic:

The annoyance of having to keep on procuring more and more products which eventually run out– such as hair gel/wax, toothpaste, shampoo, etc.

Alternatives:

Brushing your teeth with just Himalayan pink sea salt? Instead of putting wax/gel into your hair just wear a black baseball cap? Instead of shampoo, just use simple white bar soap in both your body *and* your hair?

I also think that hand bar soap is insanely under-rated. Use that instead of those wasteful ‘Soft Soap’ pumping dispensers?

For cleaning surfaces just use really hot water?