Hey mate, everyone will have different opinions on this, but I’ll give you my take
If you have cheap electric under 5c/kw and are able to write off electric costs as tax deductible OR re use the heat for pool, spa, underfloor heating then yes it is because old Gen machines are under $300.
Let’s do an example
If you have 5c electric and you can write off 50% of your power, then your power is 2.5c
S19 95T miners are selling for under $100. One miner generates $4.50 a day, after taxes you pay $1.92 in power which gives you $2.58 a day in profit. You’d get your money back in 40 days and they’d make you money until the next halving.
Or another example is if you re use the heat from water cooling plates, thats power you’re already using and you’re getting money back from it (assuming heat efficiency is the same)
Those are the times you’ll actually get more btc back from the btc used to buy the machine. Hope that makes sense.