They aren't useless the secure the network.
If you decide to open a bank so you pay a contractor a lot of money to build a secure vault, and then you install lots of cameras, pay for an alarm system, and hire security guards .... and then the bank never gets robbed (maybe because the security is too tight) was it a waste of resources?
So are you saying that the process of mining is purely validating transactions? I apologise for my question if that is the case, I had the impression most mining calculations were akin to brute force calculations looking for special numbers that match the formula - similar to hunting for prime numbers. Have I got this all wrong then?
Yes, the mining secures the blockchain. The 25 bitcoins that the miner receives is totally worth the security provided. You aren't the first person to misunderstand this process. It is partly a language thing, but using terms like "Securing" & "Securers" just doesn't flow easily off the tongue.
The Bitcoin protocol fits all together as a very elegant operation. When the media complains about one aspect or another about how Bitcoin works, it is a bit like complaining about how math, logic, or computers work.