I plan on living and shooting at least 30 more years.
Per month, I (currently) want to shoot 400 22lr, 300 9mm, 200 .40s&w, 200 .45acp, 60 7.62x39, 100 .223, and 50 .308.
How much is enough?
30*12 = 360 months of shooting
144,000 rnd of .22lr
108,000 rnd of 9mm Luger
72,000 rnd of .40 S&W
72,000 rnd of .45ACP
36,000 rnd of .223
21,000 rnd of 7.62x39
21,000 rnd of .308
That is how much ammo is currently "enough". That would make sure that I am able to continue shooting my guns without interruption for the forseeable future. This is not even what I would consider "hoarding" because it is only what I anticipate I will require.
Note: this is not how much I have. This is "how much ammo is enough" if I were buying for my anticipated use. I have about a 1000 rounds of everything, and replace as it gets used up.