It's like not having a backup drive. Everything is fine until one day it isn't.
A good UPS does more than just protect from outages. It also protects from surges and low-voltage situations that can both damage the equipment severely.
A UPS doesn't cost much and will last many years. Buying a new motherboard and GPU because they got fried is much more expensive.
Keep in mind that most equipment of this nature has universal power supplies, and thus works even at just 50% of nominal grid voltage.
The substation is mandated to trip in that anomaly, btw. Otherwise some very common types of motors (AC induction, single and 3-phase) would burn from the excessive current they draw to compensate for the reduced voltage.
A good UPS does more than just protect from outages. It also protects from surges and low-voltage situations that can both damage the equipment severely.
A UPS doesn't cost much and will last many years. Buying a new motherboard and GPU because they got fried is much more expensive.