...CH a veteran miner with miners in hand and actual data on BTC ROI is telling you on all the machines he bought he would have had more BTC in hand by buying and holding than mining, and if you want more real maths historical data has shown buying and holding has been significantly more profitable for 99.9% of miners than buying a miner and mining.
While nothing you said is incorrect as I too have been bitten by bad miner investments - the real killer CH referrs to has been preorders where you lock in a BTC/$ ratio early then get a miner much much later than promised ...
Sucks to spend over 100BTC on a BFL only for it to arrive nearly a year later and only mine a small fraction of that. But if we would have all known the prices would go up by a few thousand % of course we would all have behaved very differently.
Buying in-hand miners that can ROI maybe 40days out (or less sometimes with altcoins as pointed out) is a much better idea, and if you can resell it (*cough* eBay) before it becomes too devalued it can provide a nice little extra profit. But basically this comes down to: importing/reselling can be more profitable than holding gear past its useful life, but then you are relying a greater fool to buy it down the road and accepting a lot of risk (paypal cracking down on BTC, freezing accounts, etc)...