excessive heat, excessive detonation, increased temps, poor oil, excessive exhaust temps etc are what kills an engine
boost is usually seperate to these, but a higher driver and can influence what kills the motor
ie high boost, high intake temp, leads to detonation, leads to piston failure and ringlands toast etc
the state of tune and compression among many other things play a part in how long it can last, or how reliable it may, or may not be
one thing for sure
the more boost, the more stress, the more heat, the more likely to detonate, the more likely to fail
ie if you can run 14psi effeciently and make good power vs
run 18psi and ring its neck for an extra 11kw, stick with 14psi
be sure every psi extra you add you gain power and torque
otherwise its pointless and increases failure rate or rapidly reduces mean time between failure
ie dont run 14psi and have a nice sweet tune
and then just add in more boost to "hope" it makes more power
check and be sure, otherwise you might be adding more heat and risk for no gain, or in some cases, less gain from increased detonation and intake temps