If you could only have one thing against any possible potential problem, duck tape probably isn’t the worst option. (A good strong knife is probably the most fundamental tool though.)
But if you are the type of person that digs making things and solving problems, you will probably spend your life learning skills and accumulating tools and processes. So when something breaks or you encounter some unforeseen problem you will very likely just repair/modify/built the thing properly and permanently.
I keep toolkits on my bikes, in my van, in my home, and I have a well equipped workshop so I’m never far from tools. And I keep cable ties and fasteners and duck tape in all those places too, but I very seldom use the duck tape.
The most I ever really use it for is very, very temporary holding in place (max a couple of minutes) while I execute some other process. 'Cos the effort involved in removing set duck tape generally isn’t (for me) worth the convenience of a quick repair.
Having said that, I would much rather be stuck on a desert island with a pallet of duck tape than without one. But would I exchange a good knife for a pallet of duck tape under those circumstances?
Dunno…
