Having played over twenty years, I hesitate to guess how many I've lost. Probably under twenty though and way fewer than I've given away to get people started in this great sport. I hardly ever throw more than one drive unless it's practice or the first hole, whereas I usually throw two. Other than water hazards, I usually have a pretty good eye for where it's going to end up by the flight pattern, and I attirbute that mostly to having had so many math classes. I firmly believe Analytic Geometry, Trigonometry and Caculus help when you see angles and distances.
Last I counted (probably 3-4 years ago) I had about 50 unaccounted for discs. Not all of them were lost; some were given away to new players, some were left out on the course (it's not just a senior thing). After that realization, I had to quit counting. It sucks to realize how much $ I've thrown away in plastic and how many cool discs I could have on my wall if I kept better track of them. Since this realization, I've been much more aware and don't lose so many.
On average I probably lose 5 a year (or donate to the water gods). Recently I adopted the idea of keeping DX plastic around just for the dang water holes. I managed to hold onto a 150 DX Eagle for months; only threw it on water holes & it always found its way back to me. Then when it's time finally came, I didn't shed a tear.
Congrats to the peeps who have only lost a few; you're my heroes!