No known cure
Take off parts aren't an issue in the used market if they come off a common size frame like a 18"/largeIMHO buying a complete bike and then upgrading all inferior components is more expensive. Complete bike is only worth it if you intend to ride it as is and the components (inc. wheels) are good enough.
If you have a specific bike and frame in mind, you can just price out what the "new complete bike + upgrades - selling take-offs" is compared to "frame+ components"
It also is harder to sell take-off parts that already are shortened since a potential buyer may not be able to fit them (i.e. short steerer, short brake hoses). also depends on your patience for the hassle selling the crap.