I think they only get loud when people have a fixed budget for a loop. To do it properly IMO, you need to list up the parts you need for a loop without really having the cost in mind. If you start trying to cut corners because you cant afford it, then something will suffer - most likely your ears.
It could be from trying to save money and getting a cheaper pump, or saving to get cheaper fans, or anything like skimping out on a cheap block / pump / rad meaning you have to turn your fans up more.
When I buy anything really I dont tend to have price in mind. Not cause I'm overly wealthy or anything, but I just like having the best things, and it gives you a greater sense of pride to own them