I mean, if it really is worth it, why wouldn't the companies/datacenters that own these servers use them to crypto mine themselves instead of renting cloud mining?
Actually many people think like this but this is wrong theory, first you need to know what is cloud mining before you get wrong conclusion.
I will give you simple example how cloud mining works for trusted services.
First you need to know what are you renting, Mega hashes or Machine, by my opinion is better to rent hashes because you will have stable mining.
If you rent machine you will get cheaper price, but if you mine ETH you should know that many offers are because that machines will reach the dag file size limit soon. Today's dag file size is 4.125 so people will rent 5gb machines because soon, dag file size is increasing around 0.72x per year but if more miners are in the game this number can increase much faster, so if you make a deal in 1-2-3 years it can be risky.
So let's say we rent Mega Hashes instead of a machine, with 1000 Mhs on this price today you can make 109$ for 24h, company that offers cloud mining include electricity price + machine renting in this price so let's say you will get something like 120-130$ per day, if you make 1 year contract it will cost you something around 45k and you will make 40k so you are losing money right?
If you rent the same hash power before 6 months, the price for 1000mhs in that time was 35-40$ or around 13k per year, first 60 days of the contract you will make 1500$ + 60 days 3000$ and last 60 days 5500$ and if the price keeps going like this in next 6 months of the contract you can make 19.620$ and if we collect the number we have 29.620 - 13.000 = 16.620$ PROFIT, of course, all this is just assumption I just want to explain the bigger picture in a simple way.