What is a core cost?

Could you please elaborate on the concept of a CORE cost? In the realm of cryptocurrency and finance, how does it play a significant role in budgeting and decision-making processes? Is it a fixed or variable expense, and how does it differ from other types of costs that businesses and individuals might encounter in this industry? Additionally, how do core costs factor into the profitability analysis and long-term financial planning of a cryptocurrency project or venture?