Assuming you have 40 years of smoking left in your life...
= 15 pounds per year
= 240 ounces per year
assuming 10 bowls per ounce
= 2400 bowls per year
assuming 300 smoking days per year
=
8 bowls of tobacco per day for 40 years
There are some people who smoke that much, but I find that idea beyond the realm of reason for my particular lifestyle. But there are many lifestyles, and YMMV, truly. Wow.

Of course, if you really have as many decades as that ahead of you, you may wish to continually infuse blends of certain types, to enjoy not just aged tobacco, but vertical flights or A/B comparisons. I have found these to be very interesting, and worth doing. So don't necessarily count yourself done just yet!
All this assumes you are cellaring with the intent to smoke the tobacco. You may cellar to collect (sell, trade) later on as well. Many people do.
600 pounds is remarkable. A kid's college education, in tobacco form.