I know that people have made a profit from investing into BTC hardware with FIAT. But at no time, where a Investment into mining hardware with BTC profitable in terms of USD.
(I don't count the time when BTC was 1200 USD and then some hardware was bought)
What you wrote makes my brain hurt.
Rising BTC prices hedge risk and improve profits when investing in mining hardware. It DOESN'T factor at all in if you are making/losing BTC directly by mining.
Your comments make NO sense.
"Investing" in mining hardware with FIAT or BTC is exactly the same thing except for any fee difference in the transaction with one or the other. If anyone says different they are fooling themselves.
If I have a $1000 today... I can buy BTC or I can buy a mining rig (whether that is in USD or BTC only matters in fees). A mining rig is technically only profitable if it mines more BTC then its purchase price (in BTC) was. Sure rising prices can mitigate the risk of mining by allowing a USD profit... but that profit would still be lower then if you just bought BTC thus just a hedge against loss.
People make BTC profit from mining all the time... if they didn't there wouldn't be pentahashes added almost daily. Yes right now ASICs and business's are squeezing most profits out of mining but it does occur.
To the OP: Hash probably lags price a bit since it is reactionary and takes time to order/setup mining rigs etc (and to take them down). It also will be less and less of a factor as mined BTC become less and less a % of available coin.