Same as any other rig for anything. Higher load usually doesn't make much difference in lifetime.

The problem with components is that they can break one day after you bought it, or last 50 years.

For example, in CERN they bought 100,000 disk drives for their huge amount of data. Lets say disk lifetime is 1M hours which is 114 years, so sounds pretty good. But that means, on average, every 10 hours one of their drives will fail.