Blood Essence contains the fruit of cultivation and giving too much of it away too quickly can not only damage a cultivator's foundation but it will lower your cultivation in the short term.
@Shi. ight so from my puny martial arts understanding that uses blood essence basically its like a form of life, like true qi you can burn it off and when you burn it off you never get it back it's gone you only have a select few in your body before you have no more