1 piece steel cranks doing this is for "cheap" metal, machining done wrong or both.
Cheap pedals won't help either.
Re-threading cranks often won't last long even if works very short term.
Most cranks don't have enough metal left to use a "helicoil" etc. so the crank hole can break w/o warning.
Cheap pedals can strip it's threads leaving crank hole full of crap... If this is your problem, Carefully Running a tap to clean the crank threads might work. Have to be very careful starting the tap or will ruin the crank.
If you have 3 part crank, can have similar problems.
Plus alloy parts can strip threads easier for cross threading, over torquing the pedals or using cheap pedals w/ crap thread.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave