I reached that point a few (maybe 3) years ago. I had so many extras and duplicates that it was hard to find and use the stuff I really wanted and needed. I've since then sorted out many duplicates and things that have been upgraded and sold them off. I've used those funds to buy exactly the things that I wanted and didn't want to pay the high prices for. So, traded off the excess for what I really wanted, at no cost. Overall, right sizing my supersized helping of tools was just like when I lost weight. I feel a whole lot better now, and wouldn't go back, no matter how tempting "just one more helping" is.
Mind you, I'm not a minimalist in any way. I have a very complete and quite nice set of garage tools for working on cars. It's a mix of Snap-on and Proto and a few other select items. Enough to fill a 26" stack and a 42" stack box.
Then, I have a Proto nostalgia set that I have collected. Parts of it reside with the garage stuff, and parts of it get pegboarded in my basement shop. It's really just a collection, it's surplus to the basic needs that are met with the garage boxes, minus the extra Proto. But, it saves me going from the garage to the shop for a tool.
Then, I have a very complete Snap-on set in a portable "on the road" box. That set is more complete than most non-pro garage 26" stacking combo box sets. It saves raiding my garage tools and throwing an emergency box together when I make a trip or have to do an on the road repair for some reason.
Three sets, meet three different "needs" I perceive. Any one set could probably do for 90% of what I do, and I could make do easily. However, now I don't have the 3000 extra sockets, 500 extra wrenches, dozens of pliers, screwdrivers, etc, etc, etc, that I have sold over the past 3 years. Those were "too much", and I finally realized that and disposed of them, and feel a lot better about my tools now. Those thousands of tools have been replaced with some nice Snap On and Proto stuff that I was missing, and that fits in with my overall scheme of things a lot better than the superfluous extras did.
So, the question: is there such a thing as too many tools? Yes, there can be if they don't meet the basic objectives of what you want them for. If your basic objective is to have nice, beautifully matched sets to work with (that was my objective) then accumulating random stuff anytime you can afford it is too many tools. If your objective is to collect things because you love finding and buying them cheap, and hoarding them, it's unlikely you'll get "too many tools" until your house collapses and your wife leaves you for a less cluttered space. Even then, it might not be too much for you, if that's your thing.
So, the best way to answer that for yourself is look at why you own tools, and see if what you own matches the why, or exceeds it, or doesn't meet it. If not, and it doesn't match because you have excess beyond what you want, then you're at the too many tools stage.