$BTC Why are the prices of Bitcoin spot and futures inconsistent?

Definitions of Spot and Futures

Spot: Transactions and deliveries made at the current market price, trading the Bitcoin itself, requiring full capital.

Futures: Based on expectations of future prices, trading price fluctuations, requiring only margin (leverage), can be held long-term, with no fixed delivery date.

Reasons for Price Differences

Spot and futures should theoretically converge around Bitcoin prices, but there are actual discrepancies, mainly due to: