I have had my ER4XRs since October 2016, and they are still going strong today. I have showered with them regularly, slept with them
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, used them in the rain, snow, cold weather, warm weather, stuffed them in pockets, used on road trips, and essentially used them daily, and still use them today (I actually happened to try these with an OCC silver cable, and it made these warmer and filled out the somewhat anemic low end wonderfully). I would estimate I have 1000-2000 hours+ on these of playtime.
Basically, they have survived the onslaught of humidity and temperature differences that I have thrown at them. The IEMs themselves are absolutely excellent, I really cannot say enough good about these. The cable is very durable as well, but as with any cable, enough snags on doorknobs will overcome them, but a replacement cable is only $50, which is not bad. Additionally, balanced armatures are reasonably durable themselves (just don't drop them too much).
In fact, I would argue that outside of custom IEMs, you would be hard pressed to find any IEM that combines this level of comfort, isolation, SQ, and durability in one package. You can find IEMs that best these in one, or maybe two categories, but never all 4. Especially isolation vs. SQ, that is a very common tradeoff.