Using a join to compute users' HP is overkill and makes your queries less readable. Use variables:

DECLARE @HPV AS DECIMAL(18 ,8) = (SELECT hive_per_vest FROM DynamicGlobalProperties)

SELECT TOP 50 
    name, 
    reputation_ui, 
    vesting_shares * @HPV AS [Hive_Power]
FROM
    Accounts
ORDER BY 
    reputation_ui DESC