For some they're like clamps, you always need one more then what you've got.
I'd say if you have so many you can't organize them, sort them and find the ones you need when you need them then you have too many. I've come to find organization is the biggest key, nothing ruins a project or an effort more then having to find the tool that's lost wherever and just buying another to add to the clutter isn't the solution.
One of my tactics is that all of my electrical tools are in one bag; screwdrivers, pliers, wrenches, whatever. If I ever had to use it for an electrical job it goes in the bag and never comes out unless its for electrical. Have the same for plumbing. In the basement I have a HF side cabinet that holds all the bicycle repair tools while in the shop is the main cabinet with its assortment and each woodworking tool have the tools they need at them. So although I would have once thought having 3 1" wrenches was excessive I have one in the bicycle cabinet for use on the cassette and bb pullers which need them, one in the main tool box should I need it for whatever, and one at the radial arm saw so I can change blades without looking for a wrench. So for me its become quality and ease of accessibility that determines what's too much. I also have 80+ clamps hanging on the wall and I still need one more so I might not be the best example.