I imagine that is hard to do for economic reasons. For example, let us say they can sell the hardware at 14 cents, and buy at 10 cents. If you buy a contract they need to buy the hardware, i.e., they make a margin of 4 cents (but need to pay for electricity, maintenance, IT, support etc). So let's say this leaves a profit of 1 cent.

Now six months later, hardware prices drop to 5 cents (just to give an example). They will have to sell contracts for 7 cents by then (because of competition). They simply cannot compensate from their profit to upgrade old users to the new prices (at least to the same extent). However, old users were already mining for 6 months under lower difficulty, so they are partially compensated.

Mining is a risky game. Basically it is a bet on difficulty and price. If I have another 1000 Euro to invest I would again invest them in mining. Is it a safe bet? No, for sure not. It is a risky game that you have to enjoy. But so is buying BTC (if you bought at 1000$ you know what I mean . In any case it is fun to mine different coins and to support the altcoin universe.