Depends on your PSU.
If it's well constructed and you don't have any part of the ground that can come into contact with live wires, then it's not likely to be a problem.
The issue tends to be either people not connecting wires securely (which come loose), or the insulation comes off leaving them exposed.
When I terminate wires, I tend to cover all the existing wires with heatshrink, thereby giving them a second layer of insulation. This means that if the first degrades it's not exposed. If the outside gets worn away, the inside will still be intact. It's not foolproof, but it's just an extra level of safety that I like having.
If it's well constructed and you don't have any part of the ground that can come into contact with live wires, then it's not likely to be a problem.
The issue tends to be either people not connecting wires securely (which come loose), or the insulation comes off leaving them exposed.
When I terminate wires, I tend to cover all the existing wires with heatshrink, thereby giving them a second layer of insulation. This means that if the first degrades it's not exposed. If the outside gets worn away, the inside will still be intact. It's not foolproof, but it's just an extra level of safety that I like having.