my first AIO was a Thermaltake Water 3.0 Extreme that i purchased in early 2014.
i ran it constantly in a gaming system for ~3 years, now it's been running at least a few hours everyday in our media center system for 4 years and still works perfectly.
next was an EVGA CLC 280 in early 2017.
used it constantly in a gaming system for 4 years, now it is residing in a friend's gaming system and still going perfectly.
many that are anti-AIO will frantically argue against them and claim that they are a bad idea because of constant failure, short life expectancy, and leaking issues but this is not the case with your average device.
i imagine many of those people were just angry or jealous that someone could buy a cheaper easy AIO and connect it in a short time rather than go crazy for hours or days designing, installing, and testing custom liquid setups.
Nzxt x61 with stock fans, ran that 24/7 for 6 straight years, only time the pc was shut off was for maintenance. What finally failed was the fans, there was never an issue with temps, even with a 4.9GHz OC on an i7-3770K.
99% of AIO's issues can be laid directly at the feet of the installer/owner. Not the AIO itself. Pumps end up leaking because the installer pushed tubing in a hard direction, pumps get lousy temps because installers are afraid of hurting the cpu so don't tighten the pump down tight, installers don't tighten the screws correctly and warp the mount etc.
If Corsair sold 1Million aios last year and suffered a 0.1% failure rate, that's 1000 dead aios, leaks, rma's. Out of that 1000, 990 were caused by the installer. That leaves 10 people with genuine factory fails. All it takes is 1 person to make a video and in a month has had 100k uninformed viewers exclaiming the freak out over a leak, who then pass that on in forums like Toms or Reddit or Facebook or YouTube and by the end of a year 10 million people are firmly convinced that AIO's and leaks are a major issue. Multiply that by the 12 years AIO's have been around and the number of opinions on the frequency of leaks and AIO bad press is staggering.
It was 10. Out of 1 Million. A 0.001% chance. Far from a major issue.
I still have a San Ace MC liquid cooling system from 2005 in daily use, cooling a 158w load. It has leaked some from yanking on the hoses too hard when moving it between multiple systems (they are very, very short) and causing minor cracks, but they were just sealed back up with some silicone tape and I have never had to add water.
There has to be a lot of stuff you own, sold with only a 90 day warranty. Surely you don't replace those every 3 months.