Having mining equipment lets me speculate on many different coins. Naturally when I bought the equipment I was (and still am) gambling on making enough profit simply by mining, to profit over the cost of the equipment, in addition to any profit from price increases.
Only in the same sense that having dollars that can be used to buy bitcoin on an exchange which is then exchanged for many different coins lets you speculate on many different coins.
I don't think that anybody is bashing mining here. The point is to drive home the principle of whether or not the initial investment capital could have yielded more wealth by simply
buying coins.
Scrypt mining doesn't give any more flexibility to get moar coinz than does buying them with bitcoin. It might be enjoyable, it might be a good way to learn more about building a PC, etc. But it doesn't
necessarily afford any benefits over buying coins. Especially since GPUs suck a lot of electricity, which also has to be factored into opportunity cost. Even the electricity used by ASIC gear is not negligible in the calculation.
Here is a perspective you may not have considered. Suppose you just buy bitcoins and then you start trading - either trading bitcoins as the price fluctuates or trading altcoins or some combination of both. You can potentially make a few mistakes and wipe out your investment. Then you have to buy more. However, if you are mining, you have a constant stream of coins coming in that you can trade, flip, etc. So it's a more passive way to keep increasing your holdings and/or recovering from your slip-ups without constantly going back to your bank account. The electricity cost isn't massive unless you have a lot of mining equipment. The amount of money you would spend to build a few megs of hashing power could easily be wiped out in one or two bad trading moves.